The T414G mitochondrial DNA mutation: a biomarker of ageing in human eye.

The mitochondrial mutation T414G (mtDNAT414G) has been shown to accumulate in aged and sun-exposed skin. The human eye is also exposed to solar harmful rays. More precisely, the anterior structures of the eye (cornea, iris) filter UV rays and the posterior portion of the eye (retina) is exposed to visible light. These rays can catalyse mutations in mitochondrial DNA such as the mtDNAT414G, but the latter has never been investigated in the human ocular structures. In this study, we have developed a technique to precisely assess the occurrence of mtDNAT414G. Using this technique, we have quantified mtDNAT414G in different human ocular structures. We found an age-dependent accumulation of mtDNAT414G in the corneal stroma, the cellular layer conferring transparency and rigidity to the human cornea, and in the iris. Since cornea and iris are two anterior ocular structures exposed to solar UV rays, this suggests that the mtDNAT414G mutation is resulting from cumulative solar exposure and this could make the mtDNAT414G a good marker of solar exposure. We have previously shown that the mtDNACD4977 and mtDNA3895 deletions accumulate over time in photo-exposed ocular structures. With the addition of mtDNAT414G mutation, it becomes feasible to combine the levels of these different mtDNA mutations to obtain an accurate assessment of the solar exposure that an individual has accumulated during his/her lifetime.

Sclerouvectomy plus intraoperative ophthalmic brachytherapy for iris-ciliary body melanomas.

BACKGROUND: Partial lamellar sclerouvectomy was designed more than 30 years ago by Jerry and Carol Shields, in order to remove melanomas that involved the ciliary body and/or the choroid, while leaving intact the outer portion of the sclera and the overlying sensory retina [1]. METHODS: We present two cases of iris-ciliary body melanoma with different size. The performed surgery was a partial lamellar sclerouvectomy plus iridectomy, complemented by intraoperative juxtalimbar ruthenium-106 brachytherapy. RESULTS: Both cases achieved anatomical success without developing chronic ocular hypotony in the postoperative period, an infrequent but possible complication [2]. Even one of them reached a best-corrected visual acuity of 0.7 after silicone oil removal and intravitreal implant of dexamethasone because of secondary macular edema. The other remains stable with counting fingers vision. In this case, the poor functional outcome might be influenced by larger size and longer evolution of the tumor, as well as the uncontrolled arterial hypertension and older age of the patient. DISCUSSION: Intraoperative ophthalmic brachytherapy may have a beneficial effect not only over neoplastic activity [2], but also over early choroidal detachments. Its pro-fibrotic/hemostatic stimulus should be further examined by comparative studies with larger cohorts, either prospectively or retrospectively. Other protective factors could be the utilization of equine pericardial grafts for covering scleral defects as well as leaving high-density silicone oil. Another key aspect is to maintain low blood pressure levels during these procedures in order to avoid intraocular hemorrhages [3], especially when the patient exceeds the sixth decade, so the anaesthesiologist will also play a decisive role in the operating room. We prefer to anticipate the likely development of lens opacification after this operation [4], performing cataract surgery at the beginning and using a Cionni capsular tension ring due to a probable zonular instability. Pars plana vitrectomy would also remove peripheral vitreoretinal tractions and seal the retina preventing a detachment. CONCLUSION: As can be observed during the surgical video, a wide range of complications could occur during a partial lamellar sclerouvectomy. Tackle them ahead of time is crucial to achieve anatomical and functional success.

Wavefront-guided photorefractive keratectomy with and without iris registration: comparison of astigmatic correction.

This study aimed to compare the visual outcomes after photorefractive keratectomy (PRK), with and without the iris registration (IR) technology. The retrospective cohort study was performed for wavefront-guided PRK using the Technolas 217z100 excimer laser system in patients with myopic astigmatism (cylinder error - 2 to - 4 diopter [D]). Eyes were divided into IR group (IRPRK) and non-IR group (non-IRPRK). Visual acuity (VA), cylindrical refraction, and the astigmatic vector components using the Alpins method were compared between the two groups preoperatively and 6 months postoperatively. Fifty IRPRK patients (66% female, mean age 30.56 ± 6.31 years) and 50 non-IRPRK (60% female, mean age 29.60 ± 5.63 years) were enrolled. The mean logMAR uncorrected VA improved from 0.89 ± 0.44 to 0.032 ± 0.05 in the IRPRK group (P < 0.001) and from 0.89 ± 0.46 to 0.042 ± 0.06 postoperatively while follow-up in the non-IRPRK group (P < 0.001). No statistically significant differences were observed between the two groups regarding mean uncorrected distance VA (P = 0.4), corrected distance VA (P = 0.5), spherical equivalent (P = 0.16), defocus equivalent (P = 0.18), and absolute cylinder (P = 0.94). More than 90% eyes were within ± 1.00 D of emmetropia in both groups. Moreover, Alpins vector analysis revealed that no significant differences were found in any astigmatic parameters between the two groups (P > 0.05). Wavefront-guided PRK independent of the IR status is effective, safe, and predictable in patients with myopic astigmatism. No statistical significance was observed supporting data for the better outcome of visual acuity and astigmatism correction using IR in comparison with a non-IR system.

Iris Colour and the Risk of Developing Uveal Melanoma.

Uveal melanoma (UM) is a global disease which especially occurs in elderly people. Its incidence varies widely between populations, with the highest incidence among Caucasians, and a South-to-North increase in Europe. As northern Europeans often have blond hair and light eyes, we wondered whether iris colour may be a predisposing factor for UM and if so, why. We compared the distribution of iris colour between Dutch UM patients and healthy Dutch controls, using data from the Rotterdam Study (RS), and reviewed the literature regarding iris colour. We describe molecular mechanisms that might explain the observed associations. When comparing a group of Dutch UM patients with controls, we observed that individuals from Caucasian ancestry with a green/hazel iris colour (Odds Ratio (OR) = 3.64, 95% Confidence Interval (CI) 2.57-5.14) and individuals with a blue/grey iris colour (OR = 1.38, 95% CI 1.04-1.82) had a significantly higher crude risk of UM than those with brown eyes. According to the literature, this may be due to a difference in the function of pheomelanin (associated with a light iris colour) and eumelanin (associated with a brown iris colour). The combination of light-induced stress and aging may affect pheomelanin-carrying melanocytes in a different way than eumelanin-carrying melanocytes, increasing the risk of developing a malignancy.

Síndrome de la transiluminación iridiana aguda bilateral. A propósito de un caso clínico / Bilateral acute iris transillumination syndrome. A case report

OBJETIVO: Presentar el caso clínico de una paciente con el síndrome de la transiluminación iridiana aguda bilateral (BAIT). MÉTODOS: El síndrome de BAIT es una nueva entidad clínica caracterizada por una transiluminación iridiana, dispersión de pigmento en la cámara anterior y una pupila en midriasis media que no responde o es poco sensible a la luz debido a una parálisis del esfínter. Los pacientes con BAIT suelen presentar dolor ocular agudo, fotofobia y ojo rojo. DISCUSIÓN: Presentamos el caso clínico de una mujer de 53 años que, tras ser tratada de una infección del tracto respiratorio superior con moxifloxacino, desarrolló un síndrome de BAIT, diagnosticado en primera instancia de uveítis anterior aguda. CONCLUSIÓN: Este es, hasta donde se conoce, el primer caso reportado en Navarra, aunque es necesaria mayor casuística para establecer patrones claros acerca de esta enfermedad

OBJECTIVE: To present a case report of a patient with a bilateral acute iris transillumination syndrome (BAIT). METHODS: BAIT syndrome is a new clinical condition characterised by severe transillumination of the iris, acute onset of pigment dispersion in the anterior chamber, and a medial mydriatic pupil that is unresponsive or poorly responsive to light, due to a sphincter paralysis. Patients with BAIT generally present with acute ocular pain, photophobia, and red eyes. DISCUSSION: The case is presented of a 53 year-old woman, who, after being treated with moxifloxacin for an upper respiratory tract infection, developed a BAIT syndrome, which was initially diagnosed as acute anterior uveitis. CONCLUSION: As far as is known this is the first case reported in Navarra, but more case reports are needed to establish clear patterns about this condition

An unexpected complication in bilateral acute iris transillumination: Cystoid macular edema.

A 47-year-old male presented with bilateral 4 + circulating pigment in the anterior chamber, diffuse iris transillumination, dilated pupils unresponsive to light, and high intraocular pressure (IOP) levels in both eyes. Visual acuity and IOP improved bilaterally with topical steroid and antiglaucomatous therapy. In the 10th month, bilateral cystoid macular edema (CME) was developed and resolved after subtenon triamcinolone injections. CME recurred after cataract surgery in the right eye which was treated with intravitreal dexamethasone implant injection. CME was recurred in the left eye and treated with intravitreal dexamethasone implant at the same setting with cataract surgery. CME can be seen in the course of bilateral acute iris transillumination (BAIT). This is the first BAIT case presenting with bilateral CME.

The pupillary light responses of animals; a review of their distribution, dynamics, mechanisms and functions.

The timecourse and extent of changes in pupil area in response to light are reviewed in all classes of vertebrate and cephalopods. Although the speed and extent of these responses vary, most species, except the majority of teleost fish, show extensive changes in pupil area related to light exposure. The neuromuscular pathways underlying light-evoked pupil constriction are described and found to be relatively conserved, although the precise autonomic mechanisms differ somewhat between species. In mammals, illumination of only one eye is known to cause constriction in the unilluminated pupil. Such consensual responses occur widely in other animals too, and their function and relation to decussation of the visual pathway is considered. Intrinsic photosensitivity of the iris muscles has long been known in amphibia, but is in fact widespread in other animals. The functions of changes in pupil area are considered. In the majority of species, changes in pupil area serve to balance the conflicting demands of high spatial acuity and increased sensitivity in different light levels. In the few teleosts in which pupil movements occur they do not serve a visual function but play a role in camouflaging the eye of bottom-dwelling species. The occurrence and functions of the light-independent changes in pupil size displayed by many animals are also considered. Finally, the significance of the variations in pupil shape, ranging from circular to various orientations of slits, ovals, and other shapes, is discussed.

Daytime eyeshine contributes to pupil camouflage in a cryptobenthic marine fish.

Ocular reflectors enhance eye sensitivity in dim light, but can produce reflected eyeshine when illuminated. Some fish can occlude their reflectors during the day. The opposite is observed in cryptic sit-and-wait predators such as scorpionfish and toadfish, where reflectors are occluded at night and exposed during the day. This results in daytime eyeshine, proposed to enhance pupil camouflage by reducing the contrast between the otherwise dark pupil and the surrounding tissue. In this study, we test this hypothesis in the scorpionfish Scorpaena porcus and show that eyeshine is the result of two mechanisms: the previously described Stratum Argenteum Reflected (SAR) eyeshine, and Pigment Epithelium Transmitted (PET) eyeshine, a newly described mechanism for this species. We confirm that the ocular reflector is exposed only when the eye is light-adapted, and present field measurements to show that eyeshine reduces pupil contrast against the iris. We then estimate the relative contribution of SAR and PET eyeshine to pupil brightness. Visual models for different light scenarios in the field show that daytime eyeshine enhances pupil camouflage from the perspective of a prey fish. We propose that the reversed occlusion mechanism of some cryptobenthic predators has evolved as a compromise between camouflage and vision.

Secondary Glaucoma due to Iridescent Crystalline Particles Masquerading as Refractory Hypertensive Uveitis in an Eye With Irradiated Iris Melanoma.

PURPOSE: We report a previously unrecognized mechanism of secondary glaucoma due to iridescent crystalline particles released from an irradiated iris melanoma. It masqueraded as refractory hypertensive uveitis following uncomplicated phacoemulsification. MATERIALS AND METHODS: A 58-year-old gentleman had an iris melanoma that underwent successful regression following irradiation with proton beam radiotherapy. Three years later an uncomplicated phacoemulsification with intraocular lens implant was performed and subsequently the patient presented with apparently "refractory hypertensive uveitis." Closer examination identified unique iridescent crystalline particles originating from a disintegrating tumor and dispersing within the anterior chamber and drainage angle. The patient developed a unilateral secondary open-angle glaucoma attributable to these particles. Ultrasound biomicroscopy of the anterior segment confirmed absence of tumor recurrence or intrascleral spread and systemic investigations ruled out distant metastases. RESULTS: The intraocular pressure was refractory to maximal medical treatment, but was eventually controlled with trans-scleral diode laser cyclo-photocoagulation. CONCLUSIONS: This is the first report of a secondary glaucoma attributable to trabecular blockage with iridescent crystalline particulate material released from a disintegrating, previously irradiated, iris melanoma. Proton beam radiotherapy and possibly phacoemulsification may have played a role in triggering the release of these previously undescribed particles from the atrophied tumor surface. This unique mechanism of secondary glaucoma needs to be kept in mind in such rare cases. Trans-scleral cyclodiode laser may be used as a good initial option in such cases to minimize potential risk of tumor seeding with incisional glaucoma surgery.

Iris Freckles a Potential Biomarker for Chronic Sun Damage.

Purpose: To investigate the role of sunlight exposure in iris freckles formation. Methods: We prospectively examined volunteers attending a skin cancer screening program conducted by ophthalmologists and dermatologists. Frequency and topographical variability of iris freckles were noted and associated with behavioral and dermatologic characteristics indicating high sun exposure. Results: Six hundred thirty-two participants (n = 360; 57% female) were examined. Mean age of all participants was 38.4 ± 18.4 years (range, 4-84 years). Of all individuals, 76.1% (n = 481) exhibited at least one iris freckle. Most freckles were observed in the inferior temporal quadrant. The presence of iris freckles was associated with higher age (participants with iris freckles: 41.8 ± 16.8 years versus participants without iris freckles: 27.6 ± 19.2 years), a high number of sunburns during lifetime (>10: 31% vs. 19%), sunlight-damaged skin (26% vs. 11%), presence of actinic lentigines (72% vs. 45%), and a high total nevus body count (>10; 78% vs. 67%). Conclusions: The association of iris freckles, behavioral factors, and dermatologic findings, as well as the topographical distribution, indicate that sunlight exposure may trigger the formation of iris freckles. The evaluation of iris freckles offers an easily accessible potential biomarker, which might be helpful in indicating sun damage on the skin associated with cutaneous malignancies. Furthermore, the evaluation of iris freckles could also be helpful in understanding the role of sunlight in several ophthalmologic diseases.

Dosimetric comparison between cone/Iris-based and InCise MLC-based CyberKnife plans for single and multiple brain metastases.

We performed an evaluation of the CyberKnife InCise MLC by comparing plan qualities for single and multiple brain lesions generated using the first version of InCise MLC, fixed cone, and Iris collimators. We also investigated differences in delivery efficiency among the three collimators. Twenty-four patients with single or multiple brain mets treated previously in our clinic on a CyberKnife M6 using cone/Iris collimators were selected for this study. Treatment plans were generated for all lesions using the InCise MLC. Number of monitor units, delivery time, target coverage, conformity index, and dose falloff were compared between MLC- and clinical cone/Iris-based plans. Statistical analysis was performed using the non-parametric Wilcoxon-Mann-Whitney signed-rank test. The planning accuracy of the MLC-based plans was validated using chamber and film measurements. The InCise MLC-based plans achieved mean dose and target coverage comparable to the cone/Iris-based plans. Although the conformity indices of the MLC-based plans were slightly higher than those of the cone/Iris-based plans, beam delivery time for the MLC-based plans was shorter by 30% ~ 40%. For smaller targets or cases with OARs located close to or abutting target volumes, MLC-based plans provided inferior dose conformity compared to cone/Iris-based plans. The QA results of MLC-based plans were within 5% absolute dose difference with over 90% gamma passing rate using 2%/2 mm gamma criteria. The first version of InCise MLC could be a useful delivery modality, especially for clinical situations for which delivery time is a limiting factor or for multitarget cases.

Corneal Crosslinking With Rose Bengal and Green Light: Efficacy and Safety Evaluation.

PURPOSE: To evaluate crosslinking of cornea in vivo using green light activation of Rose Bengal (RGX) and assess potential damaging effects of the green light on retina and iris. METHODS: Corneas of Dutch belted rabbits were de-epithelialized, then stained with Rose Bengal and exposed to green light, or not further treated. Corneal stiffness was measured by uniaxial tensiometry. Re-epithelialization was assessed by fluorescein fluorescence. Keratocytes were counted on hematoxylin and eosin (H&E)-stained sections, and iris cell damage was assessed by lactate dehydrogenase staining. Thermal effects on the blood-retinal barrier (BRB) were assessed by fluorescein angiography and those on photoreceptors, retinal pigment epithelium (RPE), and choriocapillaris by light microscopy and transmission electron microscopy. RESULTS: RGX (10-min irradiation; 150 J/cm) increased corneal stiffness 1.9-fold on day 1 (1.25 ± 0.21 vs. 2.38 ± 0.59 N/mm; P = 0.036) and 2.8-fold compared with controls on day 28 (1.70 ± 0.74 vs. 4.95 ± 1.86 N/mm; P = 0.003). Keratocytes decreased only in the anterior stroma on day 1 (24.0 ± 3.0 vs. 3.67 ± 4.73, P = 0.003) and recovered by day 28 (37.7 ± 8.9 vs. 34.5 ± 2.4, P = 0.51). Iris cells were not thermally damaged. No evidence of BRB breakdown was detected on days 1 or 28. Retina from RGX-treated eyes seemed normal with RPE cells showing intact nuclei shielded apically by melanosomes, morphologically intact photoreceptor outer segments, normal outer nuclear layer thickness, and choriocapillaris containing intact erythrocytes. CONCLUSIONS: The substantial corneal stiffening produced by RGX together with the lack of significant effects on keratocytes and no evidence for retina or iris damage suggest that RGX-initiated corneal crosslinking may be a safe, rapid, and effective treatment.

Genetic findings in treatment-naïve and proton-beam-radiated iris melanomas.

BACKGROUND/AIMS: Iris melanomas (IM) are rare and have a lower mortality than posterior uveal melanomas (UM). Our aims were to determine the prevalence of genetic changes associated with prognosis of posterior UM, in both treated and non-treated IM. METHODS: Retrospective database review and molecular analysis of all patients diagnosed with IM at the Liverpool Ocular Oncology Centre (LOOC) between 1993 and 2015. Archival pathology specimens of confirmed IM cases were analysed for chromosomal alterations, using multiplex ligation-dependent probe amplification (MLPA) or microsatellite analysis (MSA) depending on DNA yield, and BRAF mutation status. RESULTS: 5189 patients were diagnosed with intraocular melanoma at LOOC from 1993 to 2015. Of these, 303 (5.8%) patients were diagnosed with IM. Tissue samples were available for 26 IM cases. Twelve of these cases had biopsies taken post-proton beam radiotherapy (PBR). Histological subtyping showed 14 IM being spindle, 2 epithelioid and 10 were of mixed cell type. Twenty of the 26 IM cases (77%) analysed genetically were classified as either disomy 3 (n=16) or monosomy 3 (n=4). Chromosome 6p gain was detected in 4/18 (22%) IM, and polysomy 8q in 6%. BRAF mutations were not detected in any of the four IM cases examined. One patient with IM died from metastatic disease: this tumour was disomy 3 with 6p and 8q gains. All other patients were alive with no evidence of metastases at study closure. CONCLUSIONS: Chromosomal aberrations seen in posterior UM can also be demonstrated using MLPA or MSA in both treatment naïve and PBR-treated IM. Most IM display a low-metastatic risk chromosomal profile.

Engineering a Light-Attenuating Artificial Iris.

PURPOSE: Discomfort from light exposure leads to photophobia, glare, and poor vision in patients with congenital or trauma-induced iris damage. Commercial artificial iris lenses are static in nature to provide aesthetics without restoring the natural iris's dynamic response to light. A new photo-responsive artificial iris was therefore developed using a photochromic material with self-adaptive light transmission properties and encased in a transparent biocompatible polymer matrix. METHODS: The implantable artificial iris was designed and engineered using Photopia, a class of photo-responsive materials (termed naphthopyrans) embedded in polyethylene. Photopia was reshaped into annular disks that were spin-coated with polydimethylsiloxane (PDMS) to form our artificial iris lens of controlled thickness. RESULTS: Activated by UV and blue light in approximately 5 seconds with complete reversal in less than 1 minute, the artificial iris demonstrates graded attenuation of up to 40% of visible and 60% of UV light. There optical characteristics are suitable to reversibly regulate the incident light intensity. In vitro cell culture experiments showed up to 60% cell death within 10 days of exposure to Photopia, but no significant cell death observed when cultured with the artificial iris with protective encapsulation. Nuclear magnetic resonance spectroscopy confirmed these results as there was no apparent leakage of potentially toxic photochromic material from the ophthalmic device. CONCLUSIONS: Our artificial iris lens mimics the functionality of the natural iris by attenuating light intensity entering the eye with its rapid reversible change in opacity and thus potentially providing an improved treatment option for patients with iris damage.

Association between light-to-dark changes in angle width and iris parameters in light, dark and changes from light-to-dark conditions.

BACKGROUND/AIMS: To evaluate the association between light-to-dark changes in angle width parameters and iris parameters in light, dark and changes from light-to-dark conditions. METHODS: In this prospective, cross-sectional study, anterior segment optical coherence tomography images, obtained under light and dark conditions, were analysed to determine angle opening distance measured at 500 µm from the scleral spur (AOD500), trabecular-iris space area at 500 µm from the scleral spur (TISA500), iris thickness measured at 750 µm from the scleral spur (IT750), iris thickness measured at 2000 µm from the scleral spur (IT2000), iris area (IArea) and pupil diameter (PD). Multivariable linear mixed-effect regression models were used to evaluate the association between light-to-dark changes in angle width parameters (AOD500, TISA500) and iris parameters (IT750, IT2000, IArea, PD) in light, dark and changes from light-to-dark conditions. RESULTS: 534 eyes from 314 non-glaucomatous subjects were analysed. IT750, IT2000, IArea and PD in light conditions were significantly associated with light-to-dark changes in AOD500 (p<0.05). IT750, IT2000 and IArea in light conditions were significantly associated with light-to-dark changes in TISA500 (p<0.05). IT750 in dark conditions was significantly associated with light-to-dark changes in AOD500 and TISA500 (p<0.05). Light-to-dark changes in IT2000, IArea and PD were significantly associated with light-to-dark changes in AOD500 (p<0.05). Light-to-dark changes in IArea were significantly associated with light-to-dark changes in TISA500 (p<0.05). CONCLUSIONS: Evaluation of iris parameters in light, dark and changes from light-to-dark conditions demonstrated that IT750, IT2000, IArea and PD in light conditions are significant predictors of light-to-dark changes in angle width.

Evaluation of Color-Changing Effect and Complications After Nd: YAG Laser Application On Iris Surface.

BACKGROUND: The aim of this study was to evaluate the color-changing effect and adverse effects after Nd: YAG laser application on the iris surface of rabbit eyes. MATERIAL/METHODS: The study was performed on right eyes of 12 pigmented rabbits. A laser device that produces frequency doubled 532 nm wavelength Nd: YAG laser with 900 µm spot diameter was used. The laser was applied in 3 sessions at 2-week intervals, at energy levels of 0.8 mJ in Group A and 1.5 mJ in Group B. Slit-lamp examinations and measurements of intraocular pressure (IOP) using a Tono-Pen were performed before and 1 day after each laser session. Iris thickness (IT) was measured at the beginning and the end using an ultrasonic biomicroscope. The eyes were enucleated for histopathologic examination on day 60. RESULTS: On the first day after each laser session, maximum grade 1 anterior chamber flare and cells were observed in both groups. In all eyes, flare and cells disappeared at the end of the first week. There was no significant difference in the IOP and IT values between measurements performed prior to and after laser sessions during the study (p>0.05). None of the eyes showed complications such as corneal edema, hypopyon, posterior synechia, transillumination defect, or pupillary defect. In histopathological examinations, reduction in pigment density was more profound in Group B compared to Group A, which was statistically significant (p<0.019). CONCLUSIONS: There were no serious complications apart from mild transient inflammatory signs. Change in iris color was more evident at the end of the second month.

Safety of cornea and iris in ocular surgery with 355-nm lasers.

A recent study showed that 355-nm nanosecond lasers cut cornea with similar precision to infrared femtosecond lasers. However, use of ultraviolet wavelength requires precise assessment of ocular safety to determine the range of possible ophthalmic applications. In this study, the 355-nm nanosecond laser was evaluated for corneal and iris damage in rabbit, porcine, and human donor eyes as determined by minimum visible lesion (MVL) observation, live/dead staining of the endothelium, and apoptosis assay. Single-pulse damage to the iris was evaluated on porcine eyes using live/dead staining. In live rabbits, the cumulative median effective dose (ED50) for corneal damage was 231 J/cm2, as seen by lesion observation. Appearance of endothelial damage in live/dead staining or apoptosis occurred at higher radiant exposure of 287 J/cm2. On enucleated rabbit and porcine corneas, ED50 was 87 and 52 J/cm2, respectively, by MVL, and 241 and 160 J/cm2 for endothelial damage. In human eyes, ED50 for MVL was 110 J/cm2 and endothelial damage at 453 J/cm2. Single-pulse iris damage occurred at ED 50 of 208 mJ/cm2. These values determine the energy permitted for surgical patterns and can guide development of ophthalmic laser systems. Lower damage threshold in corneas of enucleated eyes versus live rabbits is noted for future safety evaluation.

[Pupillary diameter in every day situations]. / Pupillenweite in Alltagssituationen.

AIM OF THE STUDY: For the construction of true accommodating intraocular lenses and for refractive surgery a knowledge about pupil diameter in daily life is important. Sufficient data are available only in darkness. MATERIAL AND METHODS: 206 volunteers aged between 18 and 72 years without disorders influencing the pupil have been examined by means of pupillography at two luminance conditions (3 and 30 cd/m2) and 3 fixation distances (5 m, 1 m, 0.33 m). RESULTS: Pupil size decreases by 0.42 mm per decade with the darker condition and 0.25 mm per decade with brighter light. Fixation change from 5 to 1 m has hardly any influence on pupil size, changing to 0.33 m constricts the pupil by 0.43 mm at dark condition and 0.33 mm at the lighter condition. CONCLUSION: Luminance has the strongest influence on pupil size, near fixation has hardly any influence down to 1 m. The well-known age relation of pupil size in darkness is also valid for mesopic and photopic conditions. At 3 cd/m2 it was the same as reported in darkness, at 30 cd/m2 it was less in absolute numbers, but relative as compared to young adults it was approximately the same.

Light-dark changes in iris thickness and anterior chamber angle width in eyes with occludable angles.

BACKGROUND: The purpose of this study was to investigate and measure light-dark changes in iris thickness (IT) and anterior chamber angle width in eyes with occludable angles and open angles by using anterior segment optical coherence tomography (AS-OCT). METHODS: We examined 153 eyes of 153 Japanese patients with primary angle closure suspect, primary angle closure, primary angle closure glaucoma, or primary open angle glaucoma. AS-OCT was used to determine pupil diameter, IT, angle opening distance at 500 µm (AOD500), and trabecular-iris space area at 500 µm (TISA500) in each quadrant of the anterior chamber angle (superior, inferior, temporal, and nasal) under light and dark conditions. RESULTS: In the angle closure cases, IT, AOD500 and TISA500 in the dark varied significantly among the four quadrants (P < 0.05, analysis of variance). In contrast, in the open angle cases, IT, AOD500 and TISA500 in the dark did not differ significantly among the four quadrants. In the angle closure cases and the open angle cases, significant negative associations were found between IT difference [IT(light)-IT(dark)] and AOD500 difference [AOD500(light)-AOD500(dark)] (R = -0.411, P < 0.001 and R = -0.501, P = 0.001, respectively) and between IT difference and TISA500 difference [TISA500(light)-TISA500(dark)] (R = -0.475, P < 0.001 and R = -0.462, P = 0.002, respectively). CONCLUSION: Our results suggest that thickening of the iris root under dark conditions is related to the mechanism of primary angle closure. It is important to analyze both the angle structure and peripheral IT in each quadrant.

Wavelength-dependent ultraviolet induction of cyclobutane pyrimidine dimers in the human cornea.

Exposition to ultraviolet (UV) light is involved in the initiation and the progression of skin cancer. The genotoxicity of UV light is mainly attributed to the induction of cyclobutane pyrimidine dimers (CPDs), the most abundant DNA damage generated by all UV types (UVA, B and C). The human cornea is also exposed to the harmful UV radiations, but no UV-related neoplasm has been reported in this ocular structure. The probability that a specific DNA damage leads to a mutation and eventually to cellular transformation is influenced by its formation frequency. To shed light on the genotoxic effect of sunlight in the human eye, we have analyzed CPD induction in the cornea and the iris following irradiation of ex vivo human eyes with UVA, B or C. The extent of CPD induction was used to establish the penetrance of the different UV types in the human cornea. We show that UVB- and UVC-induced CPDs are concentrated in the corneal epithelium and do not penetrate deeply beyond this corneal layer. On the other hand, UVA wavelengths penetrate deeper and induce CPDs in the entire cornea and in the first layers of the iris. Taken together, our results are undoubtedly an important step towards better understanding the consequences of UV exposure to the human eye.