Accuracy of scleral transillumination techniques to identify infant ciliary body for sclerostomy and intravitreal injections.

IMPORTANCE: There is variation in the literature for sclerotomy and intravitreal injection placement in young children, ranging from 0.5 to 3.0 mm from the limbus. We assess the accuracy of scleral transillumination to identify the ciliary body in infants for safe sclerotomy and intravitreal injections in young children. BACKGROUND: The study compares the perilimbal "dark band" seen on scleral transillumination (STI) with the ultrasound biomicroscopy (UBM), and compares these measurements with the current guidelines for sclerotomy in infants. DESIGN: Prospective case series in a tertiary paediatric hospital. PARTICIPANTS: Children aged ≤36 months undergoing general anaesthesia for eye procedures. METHODS: Scleral transillumination was performed to measure the perilimbal dark band. UBM of the ciliary body region was then performed, and correlated with transillumination findings. MAIN OUTCOME MEASURES: The midpoints of STI and UBM were compared to current cadaver-based guidelines to assess the safe point for sclerotomy. RESULTS: Twenty children were recruited, 36 STI and 35 UBM measurements were obtained. The posterior edge of the dark band had good correlation with the posterior border of the ciliary body. Transillumination and UBM correlated well for midpoint measurements. The midpoint of the dark band on transillumination was confirmed to be in the ciliary body by UBM in all cases. CONCLUSIONS AND RELEVANCE: The STI technique is a useful and fast technique to demonstrate the ciliary body. The midpoint of the dark band on STI correlates well with the UBM, and has a potential use for confirming safe-entry into the posterior segment if using current guidelines. The current cadaver-based paediatric guidelines safely avoid retinal injury.

Argon laser-assisted hypotony model in the rabbit.

To investigate whether ocular hypotony formation with 360 degrees endocyclophotocoagulation is possible. Twelve male New Zealand White rabbits were used. Entire ciliary body epithelium was destructed with green laser photocoagulation after pars plana lensectomy and anterior vitrectomy in six rabbits. Endocyclophotocoagulation was not performed to the remaining six rabbits (control group). Intraocular pressure (IOP) was measured preoperatively and followed up everyday in the first week and weekly until the end of month one. All of the rabbits were sacrificed and ciliary bodies were left for gross and light microscopic examination. Mean baseline IOPs were similar in laser and non-laser group (14.8 ± 1.4 (range 12.2-17.3) vs 14.4 ± 1.4 (range 12.2-15.9), p = 0.650). Mean IOP was 6.6 ± 0.45 mmHg (range 5.9-7.1) in the laser group and 11.5 ± 1.2 mmHg (range 10.2-13.4) in the non-laser group in postoperative day 1. IOP was below 4 mmHg in all eyes on the second day and after in laser group. In the macroscopic evaluation, the entire ciliary body had a white (loss of pigmentation) and atrophic appearance in all of the eyes in the laser-treated group compared to non-laser group. In the laser group, light microscopic examination demonstrated a severe 360 degrees disruption of ciliary processes. Ciliary processes were covered with fibrin exudation consisting of fibroblasts. There was a mild inflammation with disruption or atrophy of ciliary body epithelium with cystic vacuolar degeneration. Three hundred sixty degrees endocyclophotocoagulation yielded severe ciliary epithelium damage. IOP reduction started very early and continued in hypotonic levels during follow up period.

Photokinetic Drug Delivery: Near infrared (NIR) Induced Permeation Enhancement of Bevacizumab, Ranibizumab and Aflibercept through Human Sclera.

PURPOSE: Permeation studies, with near infrared (NIR) light and anti-aggregation antibody formulation, were used to investigate the in vitro permeation of bevacizumab, ranibizumab and aflibercept through human sclera. METHODS: A vertical, spherical Franz cell diffusion apparatus was used for this scleral tissue permeation model. A photokinetic ocular drug delivery (PODD) testing device accommodated the placement of NIR LEDs above the donor chambers. An adjustable LED driver/square wave generator provided electrical energy with a variable pulse rate and pulse width modulation (duty cycle). RESULTS: Exposure to non-thermal NIR light had no effect on mAbs with regard to monomer concentration or antibody binding potential, as determined by SE-HPLC and ELISA. The optimal LED wavelength was found to be 950 nm. Duty cycle power of 5% vs 20% showed no difference in permeation. When compared to controls, the combination of non-aggregating antibody formulation and NIR illumination provided an average transscleral drug flux enhancement factor of 3X. CONCLUSION: Narrow wavelength incoherent (non-laser) light from an NIR LED source is not harmful to mAbs and can be used to enhance drug permeation through scleral tissue. The topical formulation, combined with pulsed NIR light irradiation, significantly improved scleral permeation of three anti-VEGF antibody drugs.

Riboflavin and ultraviolet A irradiation for the prevention of progressive myopia in a guinea pig model.

In this study, we evaluated the effect of oral administration of riboflavin combined with whole-body ultraviolet A (UVA) irradiation on the biochemical and biomechanical properties of sclera in a guinea pig model to control the progression of myopia. Experimental groups were administered 0.1% riboflavin solution with or without vitamin C by gavage from 3 days before myopic modeling and during the modeling process. Guinea pigs underwent 30 min of whole-body UVA irradiation after each gavage for 2 weeks. For control groups, guinea pigs were administered vitamin C and underwent either whole-body UVA irradiation without 0.1% riboflavin solution or whole-body fluorescent lamp irradiation with or without 0.1% riboflavin solution. Resultantly, myopia models were established with an increased axial length and myopic diopter. Compared with myopic eyes in the control groups, the net increase in axial length, diopter and strain assessment decreased significantly, and the net decrease in sclera thickness, ultimate load, and stress assessment decreased significantly in experimental groups. MMP-2 expression showed a lower net increase, while TIMP-2 expression showed a lower net decrease. In addition, hyperplasia of scleral fibroblasts was more active in myopic eyes of experimental groups. Overall, our results showed that oral administration of riboflavin with whole-body UVA irradiation could increase the strength and stiffness of sclera by altering the biochemical and biomechanical properties, and decreases in axial elongation and myopic diopter are greater in the guinea pig myopic model.

Puerarin, an isoflavone compound extracted from Gegen (Radix Puerariae Lobatae), modulates sclera remodeling caused by extremely low frequency electromagnetic fields.

OBJECTIVE: To evaluate the protective effect of puerarin [an isoflavone compound extracted from Gegen (Radix Puerariae Lobatae)] in scleral remodeling induced by extremely low frequency electromagnetic fields (ELF-EMFs). METHODS: Human fetal scleral fibroblasts (HFSFs) were divided into 5 groups: (a) untreated controls; (b) cells treated with ELF-EMFs; (c) cells treated with ELF-EMFs and puerarin 0.1 µM; (d) cells treated with ELF-EMFs and puerarin 1 µM; (e) cells treated with ELF-EMFs and puerarin 10 µM. Cell proliferation activity was measured by the cell-counting kit-8 assay. Matrix metalloproteinase-2 (MMP-2) activity was measured by gelatin enzymography. MMP-2 and collagenⅠ(COL1A1) mRNA, protein expression were measured by Real-Time polymerase chain reaction , Western blot analysis, respectively. RESULTS: Puerarin reduced the inhibition in cell proliferation, MMP-2 activity, mRNA, protein expression of HFSFs exposed to ELF-EMFs and enhanced the COL1A1 mRNA and protein expression. CONCLUSION: Puerarin was found to participate in the matrix remodeling process. It might be a potential agent for the treatment of extracellular matrix degradation of sclera associated with ocular conditions.

Damage threshold in adult rabbit eyes after scleral cross-linking by riboflavin/blue light application.

Several scleral cross-linking (SXL) methods were suggested to increase the biomechanical stiffness of scleral tissue and therefore, to inhibit axial eye elongation in progressive myopia. In addition to scleral cross-linking and biomechanical effects caused by riboflavin and light irradiation such a treatment might induce tissue damage, dependent on the light intensity used. Therefore, we characterized the damage threshold and mechanical stiffening effect in rabbit eyes after application of riboflavin combined with various blue light intensities. Adult pigmented and albino rabbits were treated with riboflavin (0.5 %) and varying blue light (450 ± 50 nm) dosages from 18 to 780 J/cm(2) (15 to 650 mW/cm(2) for 20 min). Scleral, choroidal and retinal tissue alterations were detected by means of light microscopy, electron microscopy and immunohistochemistry. Biomechanical changes were measured by shear rheology. Blue light dosages of 480 J/cm(2) (400 mW/cm(2)) and beyond induced pathological changes in ocular tissues; the damage threshold was defined by the light intensities which induced cellular degeneration and/or massive collagen structure changes. At such high dosages, we observed alterations of the collagen structure in scleral tissue, as well as pigment aggregation, internal hemorrhages, and collapsed blood vessels. Additionally, photoreceptor degenerations associated with microglia activation and macroglia cell reactivity in the retina were detected. These pathological alterations were locally restricted to the treated areas. Pigmentation of rabbit eyes did not change the damage threshold after a treatment with riboflavin and blue light but seems to influence the vulnerability for blue light irradiations. Increased biomechanical stiffness of scleral tissue could be achieved with blue light intensities below the characterized damage threshold. We conclude that riboflavin and blue light application increased the biomechanical stiffness of scleral tissue at blue light energy levels below the damage threshold. Therefore, applied blue light intensities below the characterized damage threshold might define a therapeutic blue light tolerance range.

Microstructural changes in sclera under thermo-mechanical effect of 1.56 µm laser radiation increasing transscleral humor outflow.

BACKGROUND AND OBJECTIVES: Pores in the sclera are a candidate pathway for aqueous transport and therefore can be utilized to decrease the intraocular pressure (IOP) in glaucomatous eyes. Since pore formation is a well-known mechanism for stress relaxation in solids, laser-induced creation of pores in cartilage increases hydraulic permeability and promotes tissue regeneration. The aim of this paper is to demonstrate the thermo-mechanical effect of non-destructive laser irradiation on microstructural changes in sclera, in particular pore formation, resulting in substantial increase of water permeability of eye tissues that can be a novel approach to normalize the IOP. MATERIALS AND METHODS: Experiments were performed ex vivo on eight eyes of four mini-pigs and in vivo on eight eyes of four rabbits using pulse repetitive laser radiation of 1.56 µm in wavelength. Twenty laser spots of 0.6 mm in diameter with laser settings (power 0.9 W, pulse duration of 200 milliseconds, pulse repetition rate of 2 Hz) resulting in substantial increase of sclera hydraulic permeability were applied on the sclera at 1-2 mm from the eye limb. Sclera and underlying structures (choroid and ciliary body) of the rabbits' eyes were examined histologically in 1 and 45 days after laser irradiation, atomic force microscope (AFM) was applied before and after laser irradiation. RESULTS: Histological and AFM examinations have clearly recognized laser-assisted stable structural alterations: rarefication of the collagen structure in the laser irradiated zone and formation of sub-micron pores. Laser-induced alterations in the structure of ciliary bodies were small in size and mainly reversible. We have proposed a possible mechanism of the arising pores stabilization due to formation of small stable gas bubbles in sclera tissue. CONCLUSIONS: It is shown, for the first time, that thermo-mechanical effect of pulse repetitive laser irradiation results in pores formation in sclera. That can be a basis of a novel, safe, and effective technique for IOP normalization due to enhancing of uveoscleral outflow under non-destructive laser irradiation of the sclera.

[Morphologically reasonable application of 1.44 microm Nd:YAG laser in ocular surgery for distant hemostasis in conjunctival and episcleral vessels].

The article discusses morphological changes in bulbar conjunctiva and episclera after experimental exposure to Nd:YAG laser radiation at 1.44 pm in comparison to the effect of diathermal coagulator Mira TR4000. The results proved the use of 1.44 microm Nd:YAG laser in ocular surgery for distant hemostasis morphologically reasonable. Non-contact and directional laser treatment is more delicate as it produces smaller irradiated area. The depth of penetration and tissue heating is very limited. Neither excessive reparation, nor scarring is found in the exposed area. On the contrary, diathermy is a contact procedure associated with irregular distribution of heat, which causes large tissue burns and necrosis with subsequent adherent scar formation.

Scleral necrosis after plaque radiotherapy of uveal melanoma: a case-control study.

PURPOSE: To identify risk factors and outcome of scleral necrosis after plaque radiotherapy of uveal melanoma. DESIGN: Case-control study. PARTICIPANTS: A total of 73 cases with scleral necrosis and 73 controls without necrosis after plaque radiotherapy. Controls were matched for anteroposterior tumor epicenter and follow-up duration. INTERVENTION: Plaque radiotherapy with iodine-125, cobalt-60, iridium-192, or ruthenium-106. MAIN OUTCOME MEASURES: Scleral necrosis. RESULTS: Of 5057 patients treated with plaque radiotherapy for uveal melanoma, 73 (1%) developed radiotherapy-induced scleral necrosis. Scleral necrosis occurred in <1% of patients (3/1140) when plaque radiotherapy was used for tumors <3 mm in thickness, 1% of patients (33/3155) with 3- to 8-mm tumor thickness, and 5% of patients (37/762) with >8-mm-thick tumors. On the basis of tumor location, scleral necrosis was detected after plaque radiotherapy of iris melanoma in 0% of patients (0/91), ciliary body melanoma in 29% of patients (67/235), and choroid melanoma in <1% of patients (6/4731). The mean time interval between plaque radiotherapy and scleral necrosis was 32 months (median, 23 months; range, 4-126 months). The mean basal dimension of scleral necrosis was 4 mm (median, 3 mm; range, 1-15 mm), equivalent to 29% of mean tumor base (median, 24%; range, 6%-100%) and 22% of mean plaque size (median, 19%; range, 5%-75%). Multivariate analysis of factors that predicted clinically evident scleral necrosis included ciliary body (P = 0.0001) and pars plana to ora serrata (P < 0.0001) locations of anterior tumor margin, tumor thickness ≥ 6 mm (P = 0.0001), and radiation dose ≥ 400 Gy to the outer sclera (P = 0.0455). Scleral necrosis remained stable in 48% of patients (35/73), increased in size/severity in 48% of patients (35/73), or progressed to scleral perforation in 4% of patients (3/73) over a mean follow-up of 79 months (median, 54 months; range, 5-351 months). Treatment of scleral necrosis included observation in 81% of patients (59/73), scleral patch graft in 14% of patients (10/73), and enucleation in 5% of patients (4/73). CONCLUSIONS: Scleral necrosis after plaque radiotherapy of uveal melanoma was detected in 1% of cases. Factors predictive of scleral necrosis included increasing tumor thickness, ciliary body and peripheral choroidal location, and higher radiation dose to sclera. Most patients (81%) did not require treatment, and 4% evolved to full-thickness perforation. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Structural and biomechanical effects of photooxidative collagen cross-linking with photosensitizer riboflavin and 370 nm UVA light on human corneoscleral tissues.

This study quantitatively investigated the immediate effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin (RF) and 370 nm UVA light in in vitro human corneoscleral collagen fibrils using histology, thickness, scanning electron microscopy, and atomic force microscopy analyses. Twenty 8 x 2 mm corneoscleral strips were dissected sagittally from donor tissue using a scalpel. Four parameters were investigated, including the density, thickness, adhesion force, and stiffness of corneoscleral tissues before and after the collagen cross-linking treatment. The RFUVA-catalyzed collagen cross-linking treatment led to an increase in the density of both corneal (8%) and scleral (23%) stromal collagens. However, there was no difference in corneoscleral thickness. Furthermore, RFUVA-catalyzed collagen cross-linking treatment led to an increased biomechanical response of corneosclera: 25 and 8% increases in corneoscleral stiffness, and 24 and 22% increases in corneoscleral adhesion force. The collagen cross-linking treatment through RF-sensitized photoreaction may cause structural and biomechanical changes in the collagen fibril network of the cornea and the sclera. This is due to narrowing of the interfibrillar spacing and the stromal edema.

Structural response of human corneal and scleral tissues to collagen cross-linking treatment with riboflavin and ultraviolet A light.

High success rates in clinical trials on keratoconic corneas suggest the possibility of efficient treatment against myopic progression. This study quantitatively investigated the in vitro ultrastructural effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin and UVA light in human corneo-scleral collagen fibrils. A total of 30.8 × 2 mm corneo-scleral strips from donor tissue were sagittally dissected using a scalpel. The five analytic parameters namely fibril density, fibril area, corneo-scleral thickness, fibril diameter, and fibril arrangement were investigated before and after riboflavin-UVA-catalyzed collagen cross-linking treatment. Collagen cross-linking effects were measured at the corneo-scleral stroma and were based on clinical corneal cross-linking procedures. The structural response levels were assessed by histology, digital mechanical caliper measurement, scanning electron microscopy, and atomic force microscopy. Riboflavin-UVA-catalyzed collagen cross-linking treatment led to an increase in the area, density, and diameters of both corneal (110, 112, and 103 %) and scleral (133, 133, and 127 %) stromal collagens. It also led to increases in corneal (107 %) and scleral (105 %) thickness. Collagen cross-linking treatment through riboflavin-sensitized photoreaction may cause structural property changes in the collagen fibril network of the cornea and sclera due to stromal edema and interfibrillar spacing narrowing. These changes were particularly prominent in the sclera. This technique can be used to treat progressive keratoconus in the cornea as well as progressive myopia in the sclera. Long-term collagen cross-linking treatment of keratoconic and myopic progression dramatically improves weakened corneo-scleral tissues.

[The study of opportunity of aqueous humor filtration increase after nondestructive laser exposure of sclera in the site of pars plana projection (experimental study)].

Increase of scleral water permeability due to formation of porous structure after exposure of pulsed periodic radiation of erbium-glass optical fiber laser with wave length 1,56 pm was demonstrated in experimental study of cadaver human eyes in vitro and eyes of experimental animals (rabbits) in vivo. Simultaneous complex laser exposure of pars plana and ciliary processes results in summation of morphological changes that provide decrease of aqueous humor secretion, uveal drainage and extension of suprachoroid space. A base for new noninvasive technology of nondestructive laser exposure in glaucoma treatment is established.

Dual-energy CT imaging of orbits during episcleral brachytherapy with Ru-106 plaques: A phantom study on its potential for plaque position verification.

PURPOSE: To investigate the potential of dual energy CT (DECT) to suppress metal artifacts and accurately depict episcleral brachytherapy Ru-106 plaques after surgical placement. METHODS: An anthropomorphic phantom simulating the adult head after surgical placement of a Ru-106 plaque was employed. Nine DECT acquisition protocols for orbital imaging were applied. Monochromatic 140 keV images were generated using iterative reconstruction and an available metal artifact reduction algorithm. Generated image datasets were graded by four observers regarding the ability to accurate demarcate the Ru-106 plaque. Objective image quality and visual grading analysis (VGA) was performed to compare different acquisition protocols. The DECT imaging protocol which allowed accurate plaque demarcation at minimum exposure was identified. The eye-lens dose from orbital DECT, with and without the use of radioprotective bismuth eye-shields, was determined using Monte Carlo methods. RESULTS: All DECT acquisition protocols were judged to allow clear demarcation of the plaque borders despite some moderate streaking/shading artifacts. The differences between mean observers' VGA scores for the 9 DECT imaging protocols were not statistically significant (p > 0.05). The eye-lens dose from the proposed low-exposure DECT protocol was found to be 20.1 and 22.8 mGy for the treated and the healthy eye, respectively. Bismuth shielding was found to accomplish >40% reduction in eye-lens dose without inducing shielding-related artifacts that obscure plaque delineation. CONCLUSIONS: DECT imaging of orbits after Ru-106 plaque positioning for ocular brachytherapy was found to allow artifact-free delineation of plaque margins at relatively low patient exposure, providing the potential for post-surgery plaque position verification.

Protective effect of 4-coumaric acid from UVB ray damage in the rabbit eye.

UV-induced oxidation damage seems to play a major role in a number of specific pathological conditions of intraocular tissues, such as cataract formation and retinal degeneration. Therefore, antioxidant and/or scavenger compounds might protect the eyes from UV-induced cellular damage. We previously reported that 4-coumaric acid (4-CA) is able to protect rabbit corneal-derived cells (SIRC) from UVB-induced oxidation damage. In this study we evaluated the protective effect of 4-CA against UVB-induced cell damage in rabbit cornea in vivo. Twelve male New Zealand albino rabbits were used; four rabbits were used as a control and received vehicle in one eye and 4-CA acid in the contralateral eye; eight rabbits were exposed to UVB rays (79.2mJ/cm(2)) and three days before to UV exposure each animal received 1 drop/day of vehicle in one eye and 1 drop/day of vehicle containing 4-CA (164ng) in the contralateral eye. Corneal and sclera tissues were removed and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) levels were measured. Superoxide dismutase (SOD) and xanthine oxidase (XO) activities were determined in aqueous humour. UVB-induced vessel hyper-reactivity was strongly reduced at 4 and 24h after UVB exposure after local treatment with 4-CA, 8-oxodGuo levels, a marker of oxidative DNA damage, were significantly increased (P<0.05) in sclera and cornea by UVB irradiation, but when 4-CA was administered to the conjunctiva in a buffered solution once a day for 3d before and 6d after UVB exposure, levels of 8-oxodGuo were similar to controls and significantly reduced (P<0.05) compared to UVB-treated corneas. XO activity in the aqueous humour was significantly increased. The administration of 4-CA for 3d before and 6d after UVB irradiation induced a small but significant (P<0.05) reduction of XO compared with control eyes. Our results indicate that the administration of 4-CA protects eye tissues, thus reducing the harmful effect of UVB radiation at low concentration, probably through its free radical scavenging and antioxidant properties. Therefore, 4-CA may be useful in protecting the eye from free radical damage following UVB exposure from sunlight, UV lamps and welding torches.

Corneoscleral necrosis after episcleral Au-198 brachytherapy of uveal melanoma.

PURPOSE: To describe the risk factors for the development of corneoscleral necrosis (CSN) and its management in patients with primary choroidal or ciliochoroidal melanoma who underwent episcleral Au-198 brachytherapy. METHODS: Clinical records of patients with symptoms of dry eye, foreign body sensation, pain, and evidence of CSN after Au-198 brachytherapy for uveal melanoma treated over a 22-year period were reviewed retrospectively. Risk factors for the development of CSN were identified and various methods of management were evaluated. The data were analyzed using multivariant analysis. A P < 0.05 was taken as a level of statistical significance. RESULTS: Of the 202 eyes of 202 patients treated with Au-198 radioactive plaque, 15 (7.4%) patients with symptomatic complaints of dry eye and pain showed evidence of CSN. First signs were noted as early as 1 month to as late as 5 years (median time 5 months) after the treatment. Risk factors for the development of CSN included tumor thickness greater than 6 mm and ciliary body involvement (P < 0.05). Associated risk factor included intraocular pressure greater than 21 mmHg. Four patients required conservative management, 11 patients required scleral patch and/or conjunctival flaps, and 6 eyes eventually required enucleation. Eyes which developed CSN were more likely to undergo enucleation compared with eyes having no evidence of CSN (P < 0.05). None of the eyes with CSN, which required enucleation because of the failed treatment, had histopathologic evidence of recurrent tumor or tumor invading sclera. CONCLUSION: Corneoscleral necrosis may occur soon or several years after Au-198 brachytherapy for uveal melanoma. Risk factors for CSN include tumor thickness greater than 6 mm, ciliary body involvement, and intraocular pressure >21 mmHg. Closer follow-up, early recognition, and timely intervention may avert serious consequences.

Augmented Subscleral Trabeculectomy With Beta Radiation and Mitomycin C in Egyptian Glaucoma Patients.

PURPOSE: Subscleral trabeculectomy is the most common surgical treatment for glaucoma. However, wound healing and scar formation may result in bleb fibrosis, leading to bleb failure. The healing response of the wound is reported to be the single most important risk factor in determining the final intraocular pressure (IOP) after glaucoma filtration surgery. Thus, we aimed to evaluate the effect of preoperative beta irradiation and intraoperative mitomycin C (MMC) treatment as combined adjuncts to subscleral trabeculectomy in the management of glaucoma in Egyptian patients. PATIENTS AND METHODS: This prospective, interventional, comparative masked clinical study was performed between October 2016 and January 2018. This study included 50 subjects, 25 of whom underwent trabeculectomy augmented by MMC intraoperatively and beta radiation preoperatively at the bleb area (patient group #1). The remaining 25 subjects underwent trabeculectomy with MMC alone (control group #2). Beta radiation was administered 5 to 7 days before the surgery as a single dose (1000 cGy) using a strontium-90 probe. MMC (0.2 mg/mL) was administered for 2 minutes. RESULTS: There was a statistically significant difference in postoperative IOP between the groups from the second week. Intraoperative hyphema occurred in 6 cases in the control group #2, whereas no intraoperative hyphema was observed in patient group #1; this difference was statistically significant. CONCLUSIONS: Subscleral trabeculectomy augmented by beta radiation and MMC gives greater control over IOP. Therefore, we recommend using beta radiation before trabeculectomy in patients who may have a high risk of developing conjunctival fibrosis.

Efficacy and safety of blue-light scleral cross-linking.

PURPOSE: To evaluate the efficacy of blue-light scleral cross-linking as well as its safety in preventing retinal damage beneath the treated sclera. METHODS: Six rabbits were unilaterally treated with topical riboflavin (0.5%) and blue light (465 nm) on the equatorial sclera using a light emitting diode source with an exposure area of 9 mm in diameter. Four weeks after the treatment, the animals were euthanized and the exposed sclera and contralateral eye sclera excised for comparative testing of biomechanical rigidity and histologic retinal cellular damage. Extensiometry was performed to evaluate the stress-strain curve of treated versus untreated sclera, and light microscopy of the treated sclera and underlying retina were also comparatively evaluated. RESULTS: Blue-light scleral cross-linking showed a three-fold increased stiffening in all tested animals in the stress-strain curve. Histological investigation revealed no retinal damage in any of the treated eyes. CONCLUSIONS: Scleral cross-linking with riboflavin and blue light (465 nm) has a stiffening effect on the sclera without histological tissue damage to the retina.

Short chain aliphatic beta-nitro alcohols for corneoscleral cross-linking: corneal endothelial toxicity studies.

PURPOSE: Recent studies suggest that short chain aliphatic beta-nitro alcohols can cross-link corneoscleral tissue under physiologic conditions. The present study was conducted to determine the cytotoxic threshold for these agents in vitro and to draw comparisons to commonly used topical ophthalmic agents. METHODS: Primary cultures of bovine corneal endothelial cells were grown to confluence in 24- and 96-well plates using standard protocol. The cells were exposed to three beta-nitro alcohols, 2-nitroethanol, 2-nitro-1-propanol, and 3-nitro-2-pentanol in a range of concentrations from 0.1 to 10 mM. After a 48-hour exposure, cell necrosis and apoptosis were evaluated using trypan blue, propidium iodide, and annexin V staining. In addition, a review of the ophthalmic literature was conducted to derive comparisons with agents commonly used in clinical practice. RESULTS: An all-or-none response was observed for each compound. Positive staining with trypan blue, propidium iodide, and annexin V occurred at identical concentrations. The most toxic of the group was 2-nitro-1-propanol. The cytotoxic level for 2-nitroethanol, 2-nitro-1-propanol, and 3-nitro-2-pentanol was 3 mM (0.0273%), 1 mM (0.0105%), and 3 mM (0.0399%), respectively. Furthermore, by comparison with several agents used in ophthalmic practice such as fluoroquinolone antibiotics, anti-proliferative agents, and benzalkonium chloride, the beta-nitro alcohols exhibit less toxicity in vitro. CONCLUSIONS: Short chain aliphatic beta-nitro alcohols exhibit favorable in vitro toxicity thresholds. The result of this study encourages further evaluation of these compounds as potential pharmacologic topical stiffening agents for corneoscleral disorders.

The impact of prescription depth, dose rate, plaque size, and source loading on the central axis using 103Pd, 125I, and 131Cs.

PURPOSE: Modern dosimetry data are not available for Collaborative Ocular Melanoma Study-based eye plaques. This report aims to provide these data for eye plaques ranging from 10 to 22 mm, and for three different low-energy, photon-emitting radionuclides. METHODS AND MATERIALS: Recent publications on brachytherapy dosimetry parameters for 103Pd, 125I, and 131Cs were evaluated for use as eye plaque reference data. These data were entered into the Pinnacle treatment planning system for 3D calculations of brachytherapy dose distributions along the central axis for depths ranging from -1 to 10 mm based on the origin positioned at the inner sclera. In accordance with the original Collaborative Ocular Melanoma Study protocol and in the absence of radionuclide-specific heterogeneity factors, inhomogeneity corrections were not applied. RESULTS: As expected due to the mean photon energies, 103Pd, 125I, and 131Cs provided increasingly penetrating dose distributions. Dose distribution tables were prepared for fully loaded plaques and for plaques with the central source(s) removed. Over the entire range of central axis depths, and for all plaque sizes and loadings, 131Cs produced minimal outer scleral doses. Similarly, 103Pd generally produced more favorable dose distributions than 125I for depths less than 4mm. CONCLUSIONS: A modern analysis of eye plaque dosimetry evaluated dose as a function of lesion height and applicator size, and showed dependence on radionuclide selection and implant duration. For a fixed dose at the prescription point, we observed higher scleral dose corresponded with lower photon energy for a variety of plaque sizes and lesion heights.