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(Investigative Ophthalmology and Visual Science. 2005;46:3616-3622.)
© 2005 by The Association for Research in Vision and Ophthalmology, Inc.
DOI:  10.1167/iovs.04-1455
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Ultraviolet Photography of the In Vivo Human Cornea Unmasks the Hudson-Stähli Line and Physiologic Vortex Patterns

Sean G. Every,1 John P. Leader,2 Anthony C. B. Molteno,1 Tui H. Bevin,1 and Gordon Sanderson1

1From the Ophthalmology Section, Department of Medical and Surgical Sciences, and the 2Department of Physiology, University of Otago, Dunedin School of Medicine, Dunedin, New Zealand.


   Abstract
Top
 Abstract
Methods
 Results
 Discussion
 References
 
PURPOSE. To perform ultraviolet (UV) macrophotography of the normal in vivo human cornea, establishing biometric data of the major component of UV absorption for comparison with the Hudson-Stähli (HS) line, the distribution of iron demonstrated by Perl stain, and cases of typical amiodarone keratopathy.

METHODS. Nonrandomized comparative case series of UV photographs of 76 normal corneas (group 1) and 16 corneas with typical amiodarone keratopathy (group 2). Image-analysis software was used to grade the major component of UV absorption for slope and the coordinates of its points of intersection with the vertical corneal meridian and inflection.

RESULTS. In group 1 the major component had a mean slope of 5.8°, sloping down from nasal to temporal cornea. The mean coordinates of points of intersection with the vertical corneal meridian and inflection were (0, 0.30) and (0.02, 0.31), respectively. No significant differences between groups 1 and 2 were found for slope (P = 0.155), intersection with the vertical corneal meridian (P = 0.517), and point of inflection (P = 0.344). The major component of UV absorption was consistent with published characteristics of the HS line, and coincidence of UV absorption and Perl-stained iron was demonstrated in one corneal button. A vortex pattern of UV absorption was observed in all corneas.

CONCLUSIONS. UV photography demonstrates subclinical corneal iron, confirming its deposition in an integrated HS line/vortex pattern. Coincident iron and amiodarone deposition occurs in amiodarone keratopathy.

Ultraviolet (UV) photography of human tissue reveals features that are not seen in visible light.1 There are few reports of human UV photography aside from applications of the Wood’s lamp in dermatology,2 3 4 5 6 7 8 forensic pathology,9 10 11 12 13 and reports of contact lens fitting with fluorescein dye.14 15

The requirements for UV photography of the ocular surface and the camera system used in this study have been reported elsewhere.16 Generic UV photography requires: (1) controlled studio illumination or appropriate filters so that only UV radiation exposes the film17 ; (2) a UV radiation source18 ; (3) a UV-transmitting lens system18 19 ; (4) a focus system20 ; and (5) UV-sensitive film.17 21 22

UV irradiation of the in vivo eye requires consideration of the spectral properties of ocular tissues and radiometric dosimetry. The ocular media act as a series of spectral filters characterized in studies of the rabbit23 and human eye,24 documenting the spectral properties of tears,25 whole cornea and its component layers,23 26 aqueous humor, and the lens.23 Kinsey23 established the threshold wavelength for corneal transmission at 290 nm, increasing to 78% transmission at 320 nm, and a threshold for lenticular transmission at 320 nm (the bandwidth 290–320 nm being absorbed by the lens).23 The action spectrum of UV keratitis27 28 and cataract29 has the lowest threshold for damage at 290 nm, whereas UV-induced free radical formation in the cornea and lens is negligible above 320 nm.29 The bandwidth of the light used to irradiate ocular tissues in the current study was 318 to 328 nm, to maximize corneal absorption and minimize light hazard. The International Commission on Nonionizing Radiation Protection has recommended an exposure limit of 1 J/cm2 over an 8-hour period for UV wavelengths incident on unprotected eyes.30 31

Preliminary UV photographs taken of the human in vivo cornea revealed a UV-absorption pattern suggestive of an integrated Hudson-Stähli (HS) line and vortex pattern.16 Our impression was that corneal ferritin32 is unmasked in UV light for the following reasons: the occurrence of maximum UV absorption at the typical location of the HS line, the similarity between corneal absorption patterns in UV light with the HS line photographed in cobalt blue light,33 and spectral absorption characteristics of ferritin in the UV region.34

The physiologic HS line composed of ferritin32 has an obscure origin that is increasingly attributed to epithelial cell migration.33 35 36 On slit lamp examination (SLE) with cobalt blue light Bron33 described the HS line as consisting of a horizontal major component, and radial minor components which converge to the inflection of the major component, and his terminology is used in this study (Fig. 1) . Bron comments that "when the [HS] line is very strongly developed, the figure produced strongly resembles the framework of a vortex pattern". Pathologic vortex patterns that occur in various inherited metabolic diseases, treatment with amphiphilic cationic drugs37 (most commonly amiodarone) and local corneal disease, are due to an opaque pigment depositing in otherwise transparent corneal epithelium unmasking a physiologic cellular arrangement.33 The purpose of this study was to investigate whether UV photography of the cornea would add new information to this field.



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  		FIGURE 1. Diagram of the major and minor components of the HS line (modified from Bron AJ. Vortex patterns of the corneal epithelium. Trans Ophthalmol Soc UK. 1973;93:455–472).

 

   Methods
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 Abstract
 Methods
Results
 Discussion
 References
 
The UV source was a broad-band xenon arc lamp with output optics of a 25-mm diameter aperture; a 5-D quartz condensing lens, to give adequate radiance intensity; and a UV band-pass transmission filter (filter number O3FIU006, 318–328 nm full width at half maximum; Carlsbad, CA). We used a conventional camera (F3 SLR; Nikon, Tokyo, Japan) with a UV 105-mm lens (Nikkor f/4.5; Nikon) confocal for visible and UV wavelengths.38 Two black-and-white films sensitive to UV wavelengths were used (initially, model XP2, Ilford, Basildon, UK39 ; and, subsequently, T-Max 400; Eastman Kodak, Rochester, NY) which has UV sensitivity down to 250 nm.22

Spectral scans of the light source with a spectroradiometer (model IL700; International Light, Newburyport, MA) and a double monochrometer/photomultiplier (GM200; International Light) determined total power in the corneal plane to be 0.1 mW/cm2. As photographs were taken with a 1-second exposure, the total exposure dose per photograph in this study was 0.1 mJ/cm2, which is one-ten thousandth of the 8-hour exposure limit for humans.31 Local ethics committee approval was granted, and the study adhered to the tenets of the Declaration of Helsinki.

Subjects were recruited at Dunedin Hospital between June 2002 and June 2003, after consultation with an ophthalmologist or in response to recruitment posters. Inclusion criteria for group 1 (normal cornea) consisted of a normal ocular surface determined by SLE, including subjects with isolated posterior segment disease or prior cataract extraction. Exclusion criteria consisted of an abnormal surface topography or ocular surface disease determined by SLE, conditions associated with iron lines other than the physiologic HS line, current contact lens wear, dry eye, ptosis, and prior anterior segment surgery other than routine cataract extraction. The inclusion criteria for group 2 required the presence of typical amiodarone keratopathy, with other inclusion and exclusion criteria being the same as for group 1.

Initial SLE of the cornea used both white and cobalt blue light—the latter increasing the ability to observe corneal iron.33 The presence of the HS line was recorded if any typically located ferritin was observed, regardless of length or intensity. Topical fluorescein was avoided before UV photography. Strict vertical positioning of the subject’s head ensured there was no head tilt that would affect orientation of the UV photographs. The lens was focused in ambient light before UV photography in darkness. Films were developed using standard processors, and the negatives were scanned into a digital format.

Using measurement functions in image-analysis software (Photoshop 7; Adobe Systems, Mountain View, CA), characteristics of the HS line were graded as described in the following list. The inferior limbus was arbitrarily assigned (x,y) coordinates of (0,0) and to enable statistical comparison of right and left eyes, we assigned the nasal cornea as positive and the temporal cornea as negative.

  1. Slope was defined as the angle in degrees of the major component to the horizontal. Estimation of the gradient was interpolative requiring superposition of a line of best fit over the major component, with the recorded value being the mean of three estimates.
  2. The coordinates of the intersection of the major component with the vertical corneal meridian.
  3. The coordinates of the inflection of the major component.
  4. Those corneas where the major component (with or without minor component contributions) could be traced across the cornea from limbus to limbus.

Student’s t-tests were used to compare groups 1 and 2 and perform subgroup analysis of group 1 for right versus left cornea, age less or more than 45 years, and male versus female. Hotelling’s T2 multivariate test was to compare the coordinates of the point of inflection in right and left eyes.

A donor formalin-fixed cornea was photographed in UV light, with subsequent Perl staining duplicating the method published by Barraquer-Somers et al.40 Using SLE in white light, we made a sketch of the pattern of amiodarone keratopathy in one subject to allow subsequent comparison with UV photographs. This was achieved by replacing the standard slit lamp eye piece with one containing a grid graticule, which was centered on the pupillary axis, enabling a sketch of the amiodarone keratopathy on grid paper.


   Results
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Discussion
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Group 1 included 76 normal corneas (38 subjects), comprising 20 women and 18 men (mean age, 47 years; range 20–82). Photographs of four subjects are shown in Figure 2 . Fifteen subjects (40%) had an HS line visible on SLE (13 bilateral, 2 unilateral) compared with 38 subjects (100%) who had a major component consistent with the HS line on UV photography. The major component, with or without contributions from minor components, was traceable across the cornea from limbus to limbus in 66 (87%) of 76 cases.



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  		FIGURE 2. Bilateral UV photographs of corneas from four normal subjects: a 34-year-old man (A), a 42-year-old man (B), a 68-year-old woman (C), and an 82-year-old man (D).

 
Group 2 consisted of 16 corneas (eight subjects; mean age, 82 years; range 73–96). The UV photograph and pattern of amiodarone deposition sketched in white light for one subject is shown in Figure 3 .



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  		FIGURE 3. An 83-year-old female with amiodarone keratopathy depicted by UV photographs (A) and a sketch of the amiodarone keratopathy seen in white light (B). The cross represents the pupillary axis.

 
The minor components that collectively give rise to a vortex pattern were evident in all subjects in groups 1 and 2 and are self-evident in Figures 2 and 3 . The mean slope of the major component in groups 1 and 2 was 5.8 ± 3.2° (SD) and 6.7 ± 1.2°, respectively, with no significant difference (P = 0.155). Subgroup analysis of group 1 showed no significant difference in slope when analyzed for age less than or more than 45 years (P = 0.864), sex (P = 0.675), or laterality (P = 0.107).

The mean coordinates of the intersection of the major component with the vertical meridian in groups 1 and 2 were (0, 0.30) and (0, 0.31) respectively, with no significant difference found (P = 0.517). Subgroup analysis of group 1 showed no significant difference when analyzed for age less than or more than 45 years (P = 0.309), sex (P = 0.382), or laterality (P = 0.687).

The coordinates of the point of inflection in groups 1 and 2 were (0.02, 0.31) and (0.02, 0.33) respectively, with no significant difference on univariate or multivariate analysis (P = 0.344). Subgroup analysis of group 1 showed no significant difference in location of point of inflection when analyzed for age less than or more than 45 years (P = 0.184), sex (P = 0.197), and laterality (P = 0.152).

Data representing the slope and coordinates of intersection with the vertical meridian and inflection for paired right and left eyes from group 1 are plotted in Figure 4 . Figure 5 shows UV photography and Perl staining of the same donor corneal button.



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  		FIGURE 4. Scatterplot of the inflection points for right and left corneas from group 1. Point I represents the mean coordinates of the inflection point. The slope of the major component in the right and left cornea is 5.5° and 6.1°, respectively.

 


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  		FIGURE 5. Correlation of the Perl staining (A) and UV absorption (B) in a corneal button.

 

   Discussion
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 Abstract
 Methods
 Results
 Discussion
References
 
The major component of corneal UV absorption was evident in UV photographs and was consistent with published data on the HS line observed in white light. The coincidence in one corneal button of UV absorption lines and corneal iron staining established that UV photography unmasked the distribution of corneal ferritin which was predominantly subclinical on SLE with white light. The HS line remains an age-related phenomenon in white light; however, it was a constant phenomenon in UV light in the population photographed in this study.

The appearance of the cornea photographed in UV light was due to absorption of UV light by ferritin highlighted against a background illuminated by unknown components of reflection, backscatter, and protein fluorescence from the cornea,41 42 iris, and lens.43 44 45 The contribution of lens fluorescence is illustrated in Figure 2D which shows a phakic left eye and a pseudophakic right eye (Implant: SI40NB; Allergan, Irvine, CA), with left corneal UV absorption highlighted by lens fluorescence. The UV absorbance of modern intraocular lenses has been described by Laube et al.46

In group 1, the prevalence of the HS line was 100% (78/78) in UV photographs compared with 40% (30/78) detected with SLE. Prevalence studies of the HS line on SLE reported by Norn47 48 and Rose and Lavin49 involved the use of white light alone. Norn47 48 excluded faint HS lines and reported prevalence rates of 29% and 18% in consecutive studies, whereas Rose and Lavin35 included them, reporting rates of 69% bilaterally and 4% unilaterally. These rates are lower than the 100% prevalence of the HS line in UV photographs reported herein. However, the results of histologic studies staining for corneal iron are consistent with our findings. Gass50 reported iron in 95% of stained corneas including 10 from subjects younger than 21 years, and Barraquer-Somers et al.40 demonstrated the HS line in 90% of stained corneas.

In group 1 the mean slope of the major component was 5.8° ± 3.2° sloping down from nasal to temporal cornea. We do not consider it possible to determine accurately the gradient of the HS line in a mobile eye with SLE, and previous studies have generally emphasized its horizontal orientation. Norn47 describes the HS line as horizontal in 61% of 406 eyes, stating that in subjects with bilateral HS lines, the lines usually sloped from nasal down to temporal cornea with the opposite slope observed in only 2 of 406 eyes. Rose and Lavin35 describe the HS line as generally horizontal in the temporal cornea, rising in the nasal cornea. Bron33 described the HS line as horizontal; however, his illustration of a right eye with a well-developed HS line photographed in cobalt blue light, shows it sloping down from nasal to temporal cornea.

In group 1 the coordinates of the intersection of the major component with the vertical meridian were calculated at (0, 0.29) and are consistent with published data. Norn47 reports the mean height of the HS line to be 3.7 mm above the inferior limbus in 168 eyes. Given that the mean vertical corneal diameter in the adult population is 11.7 mm,51 52 the coordinates are (0,0.32), and they have been usefully approximated to the junction of the middle and inferior thirds of the cornea.53

The coordinates of the inflection of the major component in group 1 were (0.02, 0.31) reflecting its location in the vertical meridian in 52 (68.4%) of 76 corneas, more nasal in 22 (28.9%) of 76 corneas and temporal in only 2 (2.7%) of 76 corneas. The data for subgroup analysis of right and left corneas is plotted in Figure 4 . Bron33 describes the minor components converging to the inflection point of the major component, and this is evident in Figures 2 and 3 .

In group 1, 87% (66/76) demonstrated a major component with or without minor component contributions, which could be traced horizontally across the cornea from limbus to limbus. Published lengths of the HS are significantly shorter; however, our impression is that the length of the HS line is largely a function of detection, and improved contrast provided by UV photographs results in increased visible lengths. Rose and Lavin49 report a length ratio of the HS line greater than half the maximum horizontal corneal diameter in only 35% of subjects bilaterally and 7% unilaterally. Gass50 and Duke-Elder54 state that the HS line does not reach the limbus, and Norn47 calculated its average length as 1.5 mm.

This study had several potential sources of error that may bias the biometric data of the major component, including errors of head or ocular alignment and measurement errors in the software (Photoshop 7; Adobe Systems). We attempted to control alignment errors by vigilant head positioning and encouraging the subject to fixate the axis of the camera lens, facilitated by prompt photography when studio lights were extinguished for UV photography. With the software, calculation of coordinates was very accurate, but estimation of the gradient was interpolative, requiring superposition of a line of best fit over the major component and systematic bias may have occurred.

Comparison of groups 1 and 2 showed no statistically significant differences for any graded feature of the major component, and Figure 3 showed coincidence of the pattern of amiodarone sketched on SLE with the lines of maximum UV absorption. This suggests that amiodarone deposition is superimposed on the physiologic pattern of ferritin deposition and that these corneal pigments are not the mutually exclusive corneal deposits they appear to be on SLE with white light. A potential confounder was the unknown UV-absorption characteristics of the corneal amiodarone lysosomal complex. It is possible that corneal amiodarone completely displaces ferritin, and if it absorbed the irradiating bandwidth 318 to 328-nm, absorption lines in UV photographs would mimic the presence of ferritin. Clarification of this would require UV spectral studies of corneal amiodarone lysosomal complex or Perl-staining corneal buttons with amiodarone keratopathy. The only UV absorption spectrophotometry of amiodarone in the literature is that of amiodarone in solution.55

The horizontal orientation of the HS line and its location at the middle and inferior thirds of the cornea are attributed by Gass50 and Lemp and Mathers56 to the line of lid closure and by Barraquer-Somers et al.40 to the inferior tear meniscus. However, there is no strong evidence that line of lid closure correlates with the location of the HS line. Spontaneous blink dynamics recorded on high speed video by Doane57 describe the lower lid primarily undergoing horizontal translation nasally on closure and temporally on opening, sometimes accompanied by a downward movement of 1 to 2 mm. This suggests that the line of lid closure is well below the location of the HS line. Bron33 suggests that the HS line occurs at the junctional fronts of centripetally migrating epithelial cells, and Rose and Lavin35 postulate that its inferior location is due to greater epithelial population pressure from the superior limbus.

Bron33 proposed that "the same growth and repair patterns of the corneal epithelium" result in generic vortex corneal patterns; however, the pathophysiology of this phenomenon remains unclear. Thoft and Friend58 synthesized contemporary knowledge regarding epithelial cell population maintenance into the X,Y,Z hypothesis, respectively describing mitotic, centripetal movement and exfoliative components in the corneal profile. Lemp and Mathers56 suggested that these components might have regional variations, proposing that centripetal epithelial cell movement (Y) in the corneal plane varies as a function of blink force applied to the corneal surface. Lavker and Sun59 stated that the limbal stem cells are compartmentalized at the limbus, indicating that movement of transient amplifying cells (X) into the corneal plane is discontinuous around the corneolimbus.

Although these observations are consistent with the development of corneal vortex patterns, they do not explain its origin. Dua and Forrester60 describe preferential circumferential migration of peripheral epithelial cells, suggesting this may impart a torsional force to epithelial cell migration; however, this was in the context of wound healing and may not be relevant to epithelial cell population homeostasis. Subsequently, Dua et al.61 demonstrated the effects of static magnetic fields on cultured corneal epithelium, suggesting that the eye acts as a dipole oriented along its anteroposterior axis, influencing the migration of cells containing magnetic compounds (e.g., ferritin). Nagasaki and Zhao62 recorded vortex patterns in a transgenic mouse expressing a green fluorescent protein, writing "the vortex is a natural consequence of many cells converging in a small central area from all directions"—reiterating Bron’s 1973 concept without further elaboration.

The source of iron incorporated into the HS line and vortex pattern is unknown. Gass50 proposes the following sources for corneal iron: tears, blood plasma, breakdown of blood in perilimbal tissues, the aqueous, and a breakdown of intracellular cytochrome enzymes. Rose and Lavin35 and Assil et al.36 presented arguments against the tear film as a source of iron and postulated the deposition of corneal iron in relatively senescent basal epithelial cells. Rose and Lavin35 emphasized the confluence of migrating sheets in the formation of iron lines in general. Cai et al.63 provided evidence that showed that ferritin in corneal epithelium protects against DNA mutations, and Applegate et al.64 show that ferritin is induced by UV irradiation of the skin. It may be that UV radiation induces corneal epithelial ferritin locally, which would be capable of scavenging free iron and minimizing consequent oxidative damage.

Future work with UV photography could include correlation of the HS line with corneal topography and high-speed video recordings of individual blink dynamics. The development of a digital camera system is desirable, and Inoue and Spring65 discuss increasing the sensitivity of charge coupled diodes to UV wavelengths.


   Footnotes
 
Supported by a Dunedin Medical School Postgraduate Research Scholarship (SGE) and the Healthcare Otago Charitable Trust (THB).

Submitted for publication December 11, 2004; revised May 15 and 28, 2005; accepted August 2, 2005.

Disclosure: S.G. Every, None; J.P. Leader, None; A.C.B. Molteno, None; T.H. Bevin, None; G. Sanderson, None

The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Corresponding author: Sean G. Every, Ophthalmology Section, Department of Medical and Surgical Sciences, University of Otago, Dunedin School of Medicine, Dunedin, New Zealand; sean.every{at}ntlworld.com.


   References
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  1. Lunnon RJ. Reflected ultraviolet photography of human tissues. Med Biol Illustr. 1976;26:139–144.
  2. Gilchrest BA, Fitzpatrick TB, Anderson RR, Parrish JA. Localization of melanin pigmentation in the skin with Wood’s lamp. Br J Dermatol. 1977;96:245–248.[CrossRef][ISI][Medline][Order article via Infotrieve]
  3. Pagnoni A, Kligman AM. Ultraviolet photography to identify early photodamage in young children. Br J Dermatol. 1997;137:321–322.[ISI][Medline][Order article via Infotrieve]
  4. Fulton JE, Jr. Utilizing the ultraviolet (UV detect) camera to enhance the appearance of photodamage and other skin conditions. Dermatol Surg. 1997;23:163–169.[CrossRef][ISI][Medline][Order article via Infotrieve]
  5. Hainer BL. Dermatophyte infections. Am Fam Physician. 2003;67:101–108.[ISI][Medline][Order article via Infotrieve]
  6. Caplan RM. Medical uses of the Wood’s lamp. JAMA. 1967;202:1035–1038.[CrossRef][Medline][Order article via Infotrieve]
  7. al-Gazali LI, Arthur RJ, Lamb JT, et al. Diagnostic and counselling difficulties using a fully comprehensive screening protocol for families at risk for tuberous sclerosis. J Med Genet. 1989;26:694–703.[Abstract/Free Full Text]
  8. Baraitser M, Patton MA. Reduced penetrance in tuberous sclerosis. J Med Genet. 1985;22:29–31.[Abstract/Free Full Text]
  9. Hempling SM. The applications of ultraviolet photography in clinical forensic medicine. Med Sci Law. 1981;21:215–222.[ISI][Medline][Order article via Infotrieve]
  10. Wallace KL, Surchard JR, Curry SC, Reagan C. Diagnostic use of physicians detection of urine fluorescence in a simulated ingestion of sodium fluorescein containing antifreeze. Ann Emerg Med. 2001;38:49–54.[CrossRef][ISI][Medline][Order article via Infotrieve]
  11. Santucci KA, Nelson DG, McQuillen KK, Duffy SJ, Linakis JG. Wood’s lamp utility in the identification of semen. Pediatrics. 1999;104:1342–1344.[Abstract/Free Full Text]
  12. Gabby T, Winkleby MA, Boyce WT, Fisher DL, Lancaster A, Sensabaugh GF. Sexual abuse of children: the detection of semen on skin. Am J Dis Child. 1992;146:700–703.[Abstract]
  13. Pang CY, Neligan P, Nakatsuka T, Sasaki GH. Assessment of the fluorescein dye test for prediction of skin flap viability in pigs. J Surg Res. 1986;41:173–181.[CrossRef][ISI][Medline][Order article via Infotrieve]
  14. Bailey N. Blacklight photography of the eye. Contacto. 1961;5:91–96.
  15. Rutherford A. Ultra-violet fluorescence photography in ophthalmology. Med Biol Illustr. 1973;23:204–205.
  16. Molteno AC, Wynn-Williams G, Every SG, Bevin TH. Photography of the living human cornea in ultraviolet light. Australas Phys Eng Sci Med. 2004;27:22–24.[Medline][Order article via Infotrieve]
  17. Lunnon RJ. Ultraviolet photography. Williams R eds. Medical Photography Study Guide. 1984;225–233. MTP Press Limited London, UK.
  18. Parrish JA, Urbach F, Pitts DG. UV-A: Biological Effects of Ultraviolet Radiation with Emphasis on Human Responses to Longwave Ultraviolet. 1978;7–35. Plenum Press New York, NY.
  19. Hansell P. Ultraviolet and fluorescence recording. Engel CE eds. Photography for the Scientist. 1968;363–383. Academic Press London, UK.
  20. Nieuwenhuis G. Lens focus shift required for reflected ultraviolet and infrared photography. J Biol Photogr. 1991;59:17–20.[Medline][Order article via Infotrieve]
  21. McMullan RF. Photography of the cornea irradiated with UVR (thesis). 1991; University of Otago Dunedin, New Zealand.
  22. Williams RW, Williams G. Reflected Ultraviolet Photography. ;May 2002. Available at http://www.msp.rmit.edu.au/Article_01/04.html. Accessed October 29, 2003
  23. Kinsey VE. Spectral transmission of the eye to ultraviolet radiations. Arch Ophthalmol. 1948;39:508–513.[ISI][Medline][Order article via Infotrieve]
  24. Boettner E, Wolter J. Transmission of the ocular media. Invest Ophthalmol. 1962;1:776–783.[ISI]
  25. Michalos P, Avila EN, Florakis GJ, Hersh PS. Do human tears absorb ultraviolet light?. CLAO J. 1994;20:192–193.[Medline][Order article via Infotrieve]
  26. Kolozsvari L, Nogradi A, Hopp B, Bor Z. UV absorbance of the human cornea in the 240 nm to 400 nm range. Invest Ophthalmol Vis Sci. 2002;43:2165–2168.[Abstract/Free Full Text]
  27. Cogan DG, Kinsey VE. Action spectrum of keratitis produced by ultraviolet radiation. Arch Ophthalmol. 1946;35:670–677.[Abstract/Free Full Text]
  28. Bachem A. Ophthalmic ultraviolet action spectra. Am J Ophthalmol. 1956;41:969–975.[ISI][Medline][Order article via Infotrieve]
  29. Yamanashi BS, Hacker H, Klintworth GK. Wavelength dependence and kinetics of UV-induced free radical formation in the human cornea and lens. Photochem Photobiol. 1979;30:391–395.[ISI][Medline][Order article via Infotrieve]
  30. IRPA/INIRC Guidelines. Proposed change to the IRPA 1985 guidelines on limits of exposure to ultraviolet radiation. Health Phys. 1989;56:971–972.[ISI][Medline][Order article via Infotrieve]
  31. ICNIRP Statement. Guidelines on UV radiation exposure limits. Health Phys. 1996;71:978.[ISI][Medline][Order article via Infotrieve]
  32. Iwamoto T, DeVoe AG. Electron microscopical study of the Fleischer ring. Arch Ophthalmol. 1976;94:1579–1584.[ISI][Medline][Order article via Infotrieve]
  33. Bron AJ. Vortex patterns of the corneal epithelium. Trans Ophthalmol Soc UK. 1973;93:455–472.[ISI][Medline][Order article via Infotrieve]
  34. May ME, Fish WW. The UV and visible spectral properties of ferritin. Arch Biochem Biophys. 1978;190:720–725.[CrossRef][ISI][Medline][Order article via Infotrieve]
  35. Rose GE, Lavin MJ. The Hudson-Stahli line III: observations on morphology, a critical review of aetiology and a unified theory for the formation of iron lines of the corneal epithelium. Eye. 1987;1:475–479.
  36. Assil KK, Quantock AJ, Barrett AM, Schanzlin DJ. Corneal iron lines associated with the intrastromal corneal ring. Am J Ophthalmol. 1993;116:350–356.[ISI][Medline][Order article via Infotrieve]
  37. Lüllman H, Lüllman-Rauch R, Wassermann O. Lipidosis induced by amphiphilic cationic drugs. Biochem Pharmacol. 1978;27:1103–1108.[CrossRef][ISI][Medline][Order article via Infotrieve]
  38. UV-Nikkor 105 mm f/4.5: Instruction Manual. 1985; Nikon Corp. Tokyo.
  39. Ilford Fact Sheet: XP2 Super. ;January 2001. Available at http://www.ilford.com/html/us_english/pdf/XP2SGB_QX.pdf. Accessed 12 May 2003
  40. Barraquer-Somers E, Chan CC, Green WR. Corneal epithelial iron deposition. Ophthalmology. 1983;90:729–734.[ISI][Medline][Order article via Infotrieve]
  41. Klang G. Measurement and studies of the fluorescence of the human lens in vivo. Acta Ophthalmol. 1948;31:1–152.
  42. Lerman S. Human ultraviolet radiation cataracts. Ophthalmic Res. 1980;12:303–314.
  43. Lerman S. An experimental and clinical evaluation of lens transparency and aging. J Gerontol. 1983;38:293–301.[ISI][Medline][Order article via Infotrieve]
  44. Lerman S, Borkman R. Spectroscopic evaluation and classification of the normal, aging and cataractous lens. Ophthalmic Res. 1976;8:335–353.[ISI]
  45. Kurzel RB, Wolbarsht M, Yamanashi BS, Staton GW, Borkman RF. Tryptophan excited states and cataracts in the human lens. Nature. 1973;241:132–133.[CrossRef][Medline][Order article via Infotrieve]
  46. Laube T, Apel H, Koch HR. Ultraviolet radiation absorption of intraocular lenses. Ophthalmology. 2004;111:880–885.[CrossRef][ISI][Medline][Order article via Infotrieve]
  47. Norn MS. Hudson-Stahli’s line of cornea. I. Incidence and morphology. Acta Ophthalmol. 1968;46:106–118.[Medline][Order article via Infotrieve]
  48. Norn MS. Hudson-Stahli’s iron line in the cornea. Occurrence in 1968 and 1988. Acta Ophthalmol. 1990;68:339–340.[Medline][Order article via Infotrieve]
  49. Rose GE, Lavin MJ. The Hudson-Stahli line. I: An epidemiologic study. Eye. 1987;1:466–470.
  50. Gass JD. The iron lines of the superficial cornea. Arch Ophthalmol. 1964;71:345–358.
  51. Klyce SD, Beuerman RW. Structure and function of the cornea. Kaufman HE Barron BA McDonald MB Waltman SR eds. The Cornea. 1988;4. Churchill Livingstone New York, NY.
  52. Pepose JS, Ubels JL. The Cornea. Hart WM, Jr eds. Adler’s Physiology of the Eye. Clinical Application. 1992; 9th Ed. 29. Mosby Year Book St Louis.
  53. Schwab IR Epstein RJ Harris DJ Pflugfelder SC Wilhelmus KR eds. External Disease and Cornea: Basic and Clinical Science Course. Section 8. 1997;246. American Academy of Ophthalmology San Francisco, CA.
  54. Duke-Elder S, Leigh AG. Diseases of the Outer Eye. Part 2. Duke-Elder S eds. System of Ophthalmology. 1965;8:985. Henry Kimpton London. part 2
  55. Ultraviolet and visible absorption spectrophotometry. British Pharmacopoeia 2001. 2001;2 The Stationary Office London. Appendix II B A133
  56. Lemp MA, Mathers WD. Corneal epithelial cell movement in humans. Eye. 1989;3:438–445.
  57. Doane MG. Interactions of eyelids and tears in corneal wetting and the dynamics of the normal human eyeblink. Am J Ophthalmol. 1980;89:507–516.[ISI][Medline][Order article via Infotrieve]
  58. Thoft RA, Friend J. The X,Y,Z hypothesis of corneal epithelial maintenance. Invest Ophthalmol Vis Sci. 1983;24:1442–1443.[Free Full Text]
  59. Lavker RM, Sun TT. Epithelial stem cells: the eye provides a vision. Eye. 2003;17:937–942.[CrossRef][ISI][Medline][Order article via Infotrieve]
  60. Dua HS, Forrester JV. The corneoscleral limbus in human corneal epithelial wound healing. Am J Ophthalmol. 1990;110:646–656.[ISI][Medline][Order article via Infotrieve]
  61. Dua HS, Singh A, Gomes JA, Laibson PR, Donoso LA, Tyagi S. Vortex or whorl formation of cultured human corneal epithelial cells induced by magnetic fields. Eye. 1996;10:447–450.
  62. Nagasaki T, Zhao J. Centripetal movement of corneal epithelial cells in the normal adult mouse. Invest Ophthalmol Vis Sci. 2003;44:558–566.[Abstract/Free Full Text]
  63. Cai CX, Birk DE, Linsenmayer TF. Nuclear ferritin protects DNA from UV damage in corneal epithelial cells. Mol Biol Cell. 1998;9:1037–1051.[Abstract/Free Full Text]
  64. Applegate LA, Scaletta C, Panizzon R, Frenk E. Evidence that ferritin is UV inducible in human skin: part of a putative defense mechanism. J Invest Dermatol. 1998;111:159–163.[CrossRef][ISI][Medline][Order article via Infotrieve]
  65. Inoue S, Spring KR. Solid-state detectors and cameras. Video Microscopy: The Fundamentals. 1997; 2nd ed. 273–326. Plenum Press New Yor.




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