Choroid and Retinal Effects of Epilepsy and Epilepsy Subgroups.

Objectives: The objective were to evaluate structural alterations in the retina and choroid tissue of epilepsy patients and subtypes using enhanced depth imaging optic coherence tomography (EDI-OCT). Methods: 46 epilepsy patients and 50 sex- and age-matched control patients were analyzed in the study. Patients' epilepsy types were recorded. The central macular thickness (CMT), retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and choroidal thickness (CT) were investigated through the Spectralis-OCT device (SD-OCT). Image-J program was used to calculate the total choroidal area (TCA), the luminal area (LA), stromal area (SA), and the choroidal vascularity index (CVI). Results: CMT, TCA, LA, and SA outcomes were substantially reduced in epilepsy patients than in healthy controls. There was no significant difference between CT, RNFL, GCL, CVI results. There were no statistically significant differences between patients with partial and generalized epilepsy (p>0.05 for each). Conclusion: According to the results of our study, epilepsy disease has effects on the posterior segment of the eye. To the best of our knowledge, our study is the first to evaluate CVI in patients with epilepsy and the epilepsy subgroups.

Regional Analysis of Inner Retinal Layer Changes in Multiple Sclerosis with and without Optic Neuritis.

Objectives: The study aimed to investigate inner retinal changes in multiple sclerosis (MS) patients by comparing them with healthy controls. The study also aimed to assess regional differences of inner retinal layer involvement in eyes with and without optic neuritis (ON). Materials and Methods: This retrospective, cross-sectional study consisted of 141 eyes of 74 relapsing-remitting MS patients and 80 eyes of 40 healthy controls. The study group was separated into two subgroups according to the presence of ON history. Peripapillary retinal nerve fiber layer (pRNFL) thickness, total macular thickness, and thicknesses of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and inner nuclear layer were compared between the MS and healthy control groups and between eyes with and without ON history. Results: Mean pRNFL, total macular, mRNFL, GCL, and IPL thicknesses were significantly thinner in the MS group than in the control group (p<0.001) and in eyes with ON compared to those without ON (p<0.05). Comparison of inner retinal layer thicknesses in the inner 3-mm ring subfields of the ETDRS grid revealed significant thinning in all subfields of the GCL and IPL of eyes with ON (p<0.05). The inferior subfield demonstrated the highest difference. Conclusion: The study demonstrated that GCL and IPL thinning is a robust and reliable biomarker in all MS patients. The thinning was significantly greater in eyes with ON than in eyes without ON. The study also documented that the inferior region showed significantly greater GCL and IPL thinning in eyes with previous ON attacks.

Electrophysiological effects of hyperbaric oxygen treatment on the healthy retina.

PURPOSE: The study aimed to investigate the electrophysiological effects of hyperbaric oxygen treatment (HBOT) on the retina after ten sessions in healthy eyes. METHODS: This prospective, interventional study evaluated forty eyes of twenty patients who were treated with HBOT of ten sessions with the diagnosis of an extraocular health problem. All patients underwent a complete ophthalmologic examination, including assessments of best-corrected visual acuity (BCVA), slit-lamp and pupil-dilated fundus examinations, full-field electroretinography (ffERG) measurements before and after HBOT within 24 h of the 10th session. The ffERG was recorded according to the International Society for Clinical Electrophysiology of Vision protocol using the RETI-port system. RESULTS: The mean age of patients was 40.5 years ranging from 20 to 59 years. Thirteen patients were administered HBOT for avascular necrosis, six patients for sudden hearing loss, and one patient for chronic osteomyelitis of the vertebra. BCVA acuity was 20/20 in all eyes. The mean spherical refractive was 0.56 dioptre (D), and the mean cylindrical refractive error was 0.75 D. Dark-adapted b-wave amplitude in 3.0 ERG was the only variable for the b-wave that showed a statistically significant decrease (p = 0.017). The amplitude of the a-waves in dark-adapted 10.0 ERG and light-adapted 3.0 ERG reduced significantly (p = 0.024, p = 0.025). The amplitude of N 1-P 1 in light-adapted 30 Hz Flicker ERG also demonstrated a statistically significant decrease (p = 0.011). Implicit times did not differ significantly in any of the ffERG data (p > 0.05). CONCLUSIONS: HBOT caused the deterioration of a-wave and b-wave amplitudes in ffERG after ten treatment sessions. The results showed that photoreceptors were adversely affected in the short term after HBOT treatment.

Choroidal thickness measurements of subjects with pseudoexfoliative syndrome and pseudoexfoliative glaucoma: A contralateral eye study.

AIM: In this study, we aimed to investigate the peripapillary choroidal thickness (PPCT) and macular choroidal thickness (MCT) in pseudoexfoliation (PEX) syndrome and compare the data of the contralateral eyes according to the presence of biomicroscopic eye involvement and glaucoma. METHOD: In this cross-sectional case-control study, PPCT and MCT measurements were analyzed in 162 eyes of 81 subjects with PEX syndrome, diagnosed biomicroscopically with the detection of PEX material. The sample included 63 eyes with pseudoexfoliation glaucoma (PG), 49 eyes with visible PEX material alone without glaucoma (PM), 50 fellow eyes without biomicroscopically visible PEX material (F), and 48 eyes of 24 healthy individuals (controls) without any sign of PEX in the detailed ophthalmologic examination. The PEX syndrome group consisted of 25 PM-F, 25 PG-F, 19 PG-PG, and 12 PM-PM eye pairs. The PPCT and MCT values were compared between the eye-pairs of the subjects with the PEX syndrome. RESULTS: The mean PPCT measurements were 183.3 ± 8.1 µm, 158.5 ± 5.4 µm, 167.8 ± 5.9 µm, and 149.9 ± 5.5 µm for the eyes in the control, F, PM, and PG groups, respectively. The eyes in the PG group had statistically significantly lower measurements than those in the control group (p < 0.01). In the contralateral eye comparison of the subjects with PEX syndrome, no significant difference was found in relation to the mean PPCT and MCT measurements between the PM-F, PG-F, and PG-PG eye pairs (p > 0.05 for all). CONCLUSION: Although the eye groups with PEX syndrome had lower mean PPCT measurements than the controls, the contralateral eye analysis of the asymmetrically involved eye pairs showed no significant differences.

Long-Term Clinical Results of Trabectome Surgery in Turkish Patients with Primary Open Angle Glaucoma and Pseudoexfoliative Glaucoma.

Objectives: The objectives of the study were to analyze the long-term results of trabectome surgery in Turkish patients with primary open angle glaucoma (POAG) and pseudoexfoliative glaucoma (PEXG) and to characterize the risk factors for failure. Methods: This single-center retrospective non-comparative study included 60 eyes of 51 patients diagnosed with POAG and PEXG, who underwent trabectome alone or phacotrabeculectomy (TP) surgery between 2012 and 2016. Surgical success was defined as a 20% decrease in intraocular pressure (IOP) or IOP≤21 mmHg and no further glaucoma surgery. Risk factors for further surgery were analyzed with the Cox proportional hazard ratio (HR) models. The cumulative success analysis was undertaken with the Kaplan-Meier method based on the time to further glaucoma surgery. Results: The mean follow-up period was 59.4±14.3 months. During the follow-up period, 12 eyes required additional glaucoma surgery. The mean pre-operative IOP was 26.9±6.8 mmHg. The mean IOP at the last visit was 18.8±4.7 mmHg (p<0.01). IOP decreased 30.1% from the baseline to the last visit. The average number of antiglaucomatous drug molecules used was 3.4±0.7 (range 1-4) preoperatively and 2.5±1.3 (range 0-4) at the last visit (p<0.01). The risk factors for further surgery requirement were determined as a higher baseline IOP value (HR: 1.11, p=0.03] and the use of a higher number of preoperative antiglaucomatous drug molecules (HR: 2.54, p=0.09). The cumulative probability of success was calculated as 94.6%, 90.1%, 85.7%, 82.1%, and 78.6% at three, 12, 24, 36, and 60 months, respectively. Conclusion: The success rate of trabectome was 67.3% at 59 months. A higher baseline IOP value and the use of a higher number of antiglaucomatous drug molecules were associated with an increased risk of further glaucoma surgery requirement.

Choroidal structural alterations and choroidal vascularity index in bipolar disorder patients.

PURPOSE: The aim of this study was to compare bipolar disorder (BD) patients with age- and sex-matched healthy individuals in order to assess the choroidal structural alterations, retinal nerve fiber layer (RNFL) thickness, and retinal changes in BD patients using encanhed depth imaging optic coherence tomography (EDI-OCT). METHOD: For this research, 39 eyes of BD patients and 36 eyes of age-matched healthy volunteers were used. Five locations were used to assess the choroidal thickness (CT): subfoveal, 500 µm nasal and 1500 µm nasal to the fovea, 500 µm temporal and 1500 µm temporal to the fovea. Image-J was used to determine the total choroidal area (TCA), luminal area (LA), and choroidal vascularity index (CVI). The Spectralis-OCT device was used to evaluate the central macular thickness (CMT), retinal nerve fiber layer (RNFL), and ganglion cell layer (GCL). The data were statistically compared. RESULTS: BD patients had significantly decreased subfoveal, nasal, and temporal CTs than controls (for all three, p = 0.0001). The results of CMT and GCL were found to be thinner than controls. (for all p = 0.0001) In comparison to the controls, the mean TCA and LA were decreased in the BD group. (p = 0.0001, p = 0.0001, respectively,). Between the RNFL and CVI values in the BD and control groups, there was no statistically significant difference (p>0.05). CONCLUSION: The results of this investigation showed that the retina and choroid of patients with BD had considerable anatomical changes.

Evaluation of the choroidal vascular index and choroidal changes in migraine subgroups.

PURPOSE: To investigate binarized choroidal structural parameters, retinal nerve fiber layer (RNFL) thickness, and retina changes duringattack-free periods in patients with migraine using enhanced depth imaging optic coherence tomography (EDI-OCT), and compare patients with migraine with aura and without aura (MwA and MoA, respectively) and aura subgroups (visual aura, non-visual aura), with age and sex-matched healthy subjects. METHOD: This observational, prospective study included 102 patients with migraine and 36 healthy controls. Central macular thickness (CMT), retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and choroidal thickness (CT) were measured using a Spectralis OCT device. The choroid vascularity index (CVI) was evaluated using the Image-J software. CVI was calculated as the proportion of the luminal area (LA) to the total choroidal area (TCA). RNFL, CMT, CT, and CVI measurements were compared statistically. RESULTS: Choroidal thickness at 1500 µm temporal of the fovea was found to be statistically significantly thinner in the MwA and MoA groups compared with the control group (p ≤ 0.01). There was a significant difference in the subfoveal CT values of the MwA and control groups (p < 0.05). The mean RNFL thickness of patients with migraine with visual aura was found to be statistically significantly thinner than in the migraine group with non-visual aura (98.73 ± 8.4 and 109.4 ± 16.8) (p < 0.05). There were no statistically significant differences between the RNFL CMT, GCC, and CVI values in the MwA, MoA, and control groups (p > 0.05). CONCLUSION: We found that the choroidal thickness was significantly decreased in patients with migraine, especially in the MwA group. In the visual aura subgroup, the mean RNFL thickness was significantly decreased compared with the non-visual aura subgroup.

Electrophysiological and anatomical outcomes of subthreshold micropulse laser therapy in chronic central serous chorioretinopathy.

BACKGROUND: To evaluate short-term efficacy of subthreshold micropulse laser therapy on chronic central serous chorioretinopathy (CSC) electrophysiologically and anatomically. METHODS: This prospective study included 18 eyes with chronic CSC. Subthreshold micropulse laser therapy was applied to the eyes using Endpoint Management System (EpM). The efficacy of the treatment was evaluated with optical coherence tomography (OCT) and multifocal electroretinography (mfERG) measurements before and after one month of the treatment. RESULTS: The mean patient age was 47.3 ± 5.7 years (ranged between 36 and 56). The mean symptomatic time of the disease was 12.7 ± 3.33 months. Central macular thickness, choroidal thickness, subretinal fluid height and width showed statistically significant decreases after EpM treatment (p < 0.05). P 1 amplitude of ring 1, 3, 4, and 5 in mfERG increased significantly (p <  0.05). CONCLUSIONS: The study demonstrated that, in both OCT and electrophysiological evaluations, EpM subthreshold laser therapy resulted in anatomical and functional improvements in chronic CSC.

Relationship between ganglion cell complex thickness and vision in age-related macular degeneration treated with aflibercept.

PURPOSE: This study aimed to analyze the correlation between ganglion cell complex thickness (GCCT) and vision compared with the choroidal thickness (CT) and central retinal thickness (CRT) in relation to the outcomes of intravitreal aflibercept treatment for choroidal neovascular membranes secondary to age-related macular degeneration (AMD). METHODS: This was a prospective, observational study. Forty-three eyes of 38 patients with wet AMD received a monthly loading dose of 2 mg aflibercept by intravitreal injection (IVI) during the first 3 months and were then followed at regular monthly intervals for an average of 10 months by a pro re nata regimen. All patients were examined using spectral domain-optic coherence tomography (OCT) and enhanced depth imaging OCT. According to their response to IVI treatment in the third month, patients were divided into 2 groups, both functionally and anatomically. RESULTS: Three-month GCCT and optic disc retinal nerve fiber layer thickness (ODRNFLT) had the most correlation with the 10-month vision (p = 0.002, p = 0.02, respectively). While baseline GCCT was most correlated with the functional response, baseline CRT was most correlated with the anatomical response (p = 0.01, p = 0.004, respectively). CONCLUSIONS: The results suggest that a reduction in 3-month GCCT indicates a good long-term vision outcome, while a reduction in 3-month ODRNFLT shows a poor long-term vision outcome. The literature suggests that this study is the first to demonstrate that baseline GCCT is more strongly correlated with the functional response than it is with CT and CRT. Hence, GCCT has a prognostic value for vision impairment.

Posterior pole analysis and ganglion cell layer measurements in Alzheimer's disease.

AIM: To compare posterior pole analysis and ganglion cell layer (GCL) of patients with Alzheimer's disease (AD) and controls. METHOD: Patients diagnosed with mild and moderate AD included in the study. Posterior pole analysis and GCL measurements were investigated by dividing the macula into superior and inferior hemifields and 5 corresponding zones. RESULTS: There were no significant differences between groups for retinal thickness measurements in any retinal zone. GCL measurements showed lower measurements in moderate AD group for GCL thickness in the superior zone 2 (p:0.025) and inferior zone 2 (p = 0.048) compared to mild AD and controls. A moderate AD status was found to cause a decrease of 5.349 µm in the GCL-SZ2 value [p:0.037]. CONCLUSION: GCL measurements in the moderate AD group show significant thinning in superior and inferior Zone 2, which may be a biomarker for AD.

The effect of hyperbaric oxygen therapy on retina, choroidal thickness, and choroidal vascularity index.

PURPOSE: To determine the acute and cumulative effect of hyperbaric oxygen therapy (HBOT) on retina and choroid tissue in healthy eyes. MATERIAL AND METHODS: Thirty-five subjects who were planned to undergo HBOT for non-ophthalmologic indications comprised the population of this prospective study. Central macular thickness (CMT), retinal nerve fiber layer (RNFL), and choroidal thickness (CT) (3 points: subfoveal area, 500 µm nasal and fovea temporal) were measured using spectral-domain optical coherence tomography (SD-OCT) before HBOT and half an hour after the 1st and 20th sessions of HBOT. The subfoveal choroidal area was segmented using ImageJ software with the binarization technique on enhanced depth imaging (EDI) OCT images. Choroidal area (CA), luminal area (LA), and stromal area (SA) were calculated. Choroidal vascularity index (CVI) was determined as the ratio between LA and CA. RESULTS: The right eyes of 35 patients aged between 22 and 59 years were enrolled in the study. The mean CMT values of the patients were 259.36 ± 22.31 µm, 256.94 ± 22.72 µm, and 254.58 ± 23.02 µm before HBOT, after the 1st session, and after the 20th session, respectively. The change in CMT values before and after HBOT was statistically significant (p=0.001). When the patients' RNFL, CT, CA, SA, LA, and CVI changes before and after the HBOT were examined, no statistically significant difference was found (p>0.05). CONCLUSIONS: Our study jointly evaluates the effect of HBOT on the vascular and stromal components of the choroid and macula in healthy eyes. Due to its thinning effect on the macula, it can be preferred as an adjunctive and facilitating treatment option in addition to current treatments in patients with macular edema due to retinal vascular disorders.

Anatomical effects of intravitreal anti-vascular endothelial growth factor injections on inner layers of the lesion-free retina.

PURPOSE: The primary aim of the study was to investigate the effects of anti-vascular endothelial growth factor (VEGF) injections on the inner retinal layer anatomy of the lesion-free retina in eyes treated for neovascular age-related macular degeneration (nAMD). The secondary aim was to compare the changes of inner retinal layers in the lesion-free region of treated eyes with the same region of the untreated, fellow eyes and, thus, to elucidate any adverse effect of anti-VEGF treatments independently of 1-year aging changes. METHODS: This was a retrospective, longitudinal, case-control study of 50 eyes of 25 patients. Twenty-five eyes with nAMD comprised the study group (16 eyes treated with aflibercept and 9 eyes treated with ranibizumab) and 25 fellow eyes with dry AMD (16 eyes in AREDS 2 and 9 eyes in AREDS 3) comprised the fellow eye group. Spectral-domain optical coherence tomography (SD-OCT) measurements were done at pre-treatment, 1 month after three loading anti-VEGF injections and at the end of 1 year. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL) thicknesses and total retinal thickness in the macula were measured. Thicknesses of inner retinal layers which were lesion-free in the outer nasal subfield of ETDRS grid were analysed and the changes in thicknesses during the follow-up period were compared between study and fellow eye groups. Paired t-test for normally distributed variables was applied for analyses of differences for the comparison of the results across the pre-and the post-. A p value of less than 0.05 was considered statistically significant. RESULTS: The mean number of injections was 5.76 ± 1.26 in the study group in 1 year. The mean decrease in total retinal thickness was significant with 6.08 ± 9.05 µm (p= 0.003) in nAMD group and was insignificant with 0.32 ± 1.03 µm (p> 0.05) in fellow eye group with dry AMD. Most of the retinal thickness decrease was during first three injections in nAMD group. Total retinal thickness and GCL thickness were thinner in the study group at every follow-up examination, but the difference between groups was not statistically significant (p> 0.05). RNFL, GCL, IPL, and INL thicknesses did not demonstrate a statistically significant change in both study and fellow eye groups during 1 year follow-up period (p> 0.05). CONCLUSIONS: Repeated anti-VEGF injections in nAMD appear to have no significant effect on the RNFL, GCL, IPL, and INL thicknesses of the lesion-free retina. Additionally, there was no significant difference in inner retinal layer changes between in eyes treated with anti-VEGF injections for nAMD and fellow eye group during 1-year follow-up.

Choroidal osteoma in a preterm infant.

Choroidal osteoma (CO) is a rare, benign, and usually unilateral intraocular tumor composed of mature bone affecting the choroid. It appears as slightly elevated, yellowish-white, or orange choroidal mass with well-defined borders. It is commonly encountered in young female adults. Here, we report findings of a 4-week-old premature baby with CO in her left eye which was detected during a routine examination for "retinopathy of prematurity." We believe that this case is the youngest patient reported with CO which showing that this pathology can be encountered even in a newborn.

A Rare Ocular Manifestation of Adult Onset Still's Disease: Purtscher's-like Retinopathy.

Adult-onset Still's disease (AOSD) is a rare multisystemic immune-mediated disease of unknown etiology with quotidian spiking fever, evanescent rash, arthralgia, and multiple organ involvement. The few AOSD cases that have been reported developed Purtscher's-like retinopathy associated with thrombotic microangiopathy (TMA). Here, we report Purtscher's-like retinopathy without TMA in a patient with AOSD. A 29-year-old-man who presented for evaluation of blurred vision was diagnosed with AOSD based on Yamaguchi criteria. He had Purtscher's-like retinopathy in his right eye. Lesions improved after steroid treatment. Although almost all reported AOSD cases with Purtscher's-like retinopathy are associated with TMA, in this case such a complication was not encountered.

Evaluation of Aflibercept Treatment Responses in Eyes with Bevacizumab/Ranibizumab-resistant Wet Age-related Macular Degeneration.

OBJECTIVES: To evaluate anatomic and functional results after switching from intravitreal bevacizumab or ranibizumab treatment to aflibercept for wet (neovascular) age-related macular degeneration. MATERIALS AND METHODS: This retrospective study included 22 eyes of 22 patients resistant to treatment with at least 6 injections of bevacizumab or ranibizumab. The first three injections had been applied monthly, the others pro re nata (PRN). Outcome measures were follow-up period, injection number, best corrected visual acuity (BCVA), central retinal thickness (CRT) and pigment epithelial detachment (PED) height. Dosing regimen of aflibercept was determined PRN. The patients were examined monthly. In all visits, BCVA and optical coherence tomography results were assessed together and injections were applied according to these findings. Patients with at least three months of follow-up were included in the study. RESULTS: Twenty-two eyes of 22 patients treated with bevacizumab or ranibizumab were switched to aflibercept therapy. Seven patients had serous PED and 4 patients had fibrovascular PED. The mean follow-up periods for these groups were 20.59±6.76 months and 8.68±3.79 months, respectively. The mean injection numbers were 10.5±3.61 vs 4.54±1.56. Statistically significant reductions were noted in CRT (533.86±164.06 µm vs 412.04±143.86 µm, p<0.05). BCVA levels were almost equal before and after switching (0.18±0.17 vs 0.18±0.14). Serous and fibrovascular PED heights decreased suboptimally from 460±281.51 µm to 282.42±175.76 µm (p>0.05) for serous PEDs and 251.25±43.85 µm to 225.75±73.09 µm (p>0.05) for fibrovascular PEDs. CONCLUSION: Switching to aflibercept resulted in significant improvement in CRT, but not in BCVA or PED heights.

Efficiency of Ozone Therapy in a Rat Model of Experimental Uveitis.

PURPOSE: To investigate efficiency of ozone therapy in uveitis. METHODS: A total of 24 albino Wistar rats were randomly assigned to four groups (n = 6); (a) control group; (b) sham group; (c) infliximab treatment group; (d) ozone therapy group. Vitreous haze scores of all groups were evaluated. Vitreous cytokine levels (TNF-α, IL-1, IL-6) measured by ELISA and eyes were enucleated for histopathologic examination. RESULTS: According to vitreous haze scores, there was statistically significant inflammation in Group (b) compared with Group (a), and there was less inflammation in infliximab and ozone groups compared with Group (b) (p < 0.05). Cytokine levels in infliximab and ozone groups were lower but not statistically significant when compared with Group (b) (p > 0.05). There was significantly less inflammation in histopathologic examination in treatment groups when compared with the sham group (p < 0.05). CONCLUSIONS: Clinical and histopathologic examination results indicate that systemic application of ozone may be efficient in the treatment of uveitis.

Comparison of Transcanalicular Multidiode Laser Dacryocystorhinostomy with and without Silicon Tube Intubation.

Aim. To compare the surgical outcomes of surgery with and without bicanalicular silicon tube intubation for the treatment of patients who have primary uncomplicated nasolacrimal duct obstruction. Methods. This retrospective study is comprised of 113 patients with uncomplicated primary nasolacrimal duct obstruction. There were 2 groups in the study: Group 1 (n = 58) patients underwent transcanalicular diode laser dacryocystorhinostomy surgery with bicanalicular silicon tube intubation and Group 2 (n = 55) patients underwent transcanalicular diode laser dacryocystorhinostomy surgery without bicanalicular silicon tube intubation. The follow-up period was 18.42 ± 2.8 months for Group 1 and 18.8 ± 2.1 months for Group 2. Results. Success was defined by irrigation of the lacrimal system without regurgitation and by the absence of epiphora. Success rates were 84.4% for Group 1 and 63.6% for Group 2 (P = 0.011). Statistically a significant difference was found between the two groups. Conclusion. The results of the study showed that transcanalicular diode laser dacryocystorhinostomy surgery with bicanalicular silicon tube intubation was more successful than the other method of surgery. Consequently, the application of silicone tube intubation in transcanalicular diode laser dacryocystorhinostomy surgery is recommended.

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.