PurposeTo examine the effect of panretinal photocoagulation (PRP) on the retinal nerve fiber layer (RNFL) thickness in patients with diabetic retinopathy.MethodsSubjects included 118 eyes for a treatment group and 164 eyes for a control group. The peripapillary RNFL thickness was measured before and 6 months after PRP in treatment group. In control group, the peripapillary RNFL thickness was measured at baseline and 6 months later. The relationships between changes in RNFL thickness and the number of laser burns, duration of diabetes, HbA1c level, and vision change were analyzed.ResultsAfter 6 months, the RNFL thickness decreased an average of 2.12 µm and 0.93 µm in the treatment and control groups. However, the changes between the two groups were not statistically significant. The relationship between the number of laser burns and changes in RNFL thickness was not significant. No differences were found between changes in the RNFL thickness and the duration of diabetes in either group. However, in the treatment group a higher HbA1c level was correlated with a greater decrease in post-PRP RNFL thickness. This relationship was not observed in the control group. The difference in the change of the RNFL thickness between the two groups was statistically significant. Vision increased an average of 0.02 and 0.01 after 6 months in the treatment and control groups, respectively. However, this difference was not statistically significant.ConclusionsAlthough a decrease in peripapillary RNFL thickness was observed in the treatment group after 6 months, it was not statistically significant compared to control group. However, the decrease was greater when the blood HbA1c level was higher.

This study evaluated the effects of glucose in human retinal pigment epithelial (RPE) cells to investigate the cause of diabetic retinal complications. Human RPE cells were cultured in media containing 5.5 mM, 11.0 mM, and 16.5 mM D-glucose. The present study performed proliferation and migration assays, and conducted western blotting for the protein expression, as well as RT-PCR for the mRNA expression, of MMP-2 and -9, and TIMP-1 and -2. The results of the western blotting analysis showed that increasing glucose concentration significantly increased the expression of MMP-2 and -9, but significantly decreased the expression of TIMP-1 and -2. Moreover, the RT-PCR results indicated significant increases in the mRNA expression of MMP-2 and -9, as well as of TIMP-1 and -2, by raising glucose concentration. This study provides fundamental data for future research on the mechanism of retinal complication in diabetic patients.

Transpupillary retinal photocoagulations were performed on ten eyes of five pigmented rabbits using a diode laser (Nidek Co., LTD, Aichi, Japan) emitting infrared radiation at 800 nm wavelength. A histological and an ultrastructural study on the treated eyes were done at 1, 3, 5, and 7 days after retinal photocoagulations. The purpose of this study was to observe the sequential changes in the retina and the choroid following transpupillary diode laser retinal photocoagulations at the parameters of laser power which produced a grayish white retinal discoloration with distinct white center. It seemed that the lesion was grade 3 retinal photocoagulation by Tso et al's classification. It appeared that the parameters necessary to produce grade 3 photocoagulation lesions were 160 mW power, and 0.2 second duration at 200 microns size. In general, with an agreement to other reports, histologic study of the diode laser lesions showed that the outer retina was damaged more severely than the inner retina. However, on day 1 after laser treatment, the alterations were more profound in the inner retina than in the outer retina and an occasional swelling of the axons in the nerve fiber layer was observed on the ultrastructural study. The results observed have not been found in other previous studies and suggest that the inner retina might be injured directly by 800 nm wavelength diode laser radiations. Thus we could conclude that 800 nm wavelength diode radiation might be absorbed by melanin pigment and also by other chromophores contained in inner retinal tissues. Further studies must follow to verify the laser-tissue interactions in diode laser retinal photocoagulations.

The author has experienced a case of microphthalmos with large orbital cyst in a 4 months old female, that was found at the time of birth. To facilitate fitting a cosmetic prosthesis, the microphthalmos with cyst was removed surgically. On serial section I could find an area of discontinuation of the sclera that was suspected to be the defective closure of the embryonic cleft. Some aberrant retinal tissue was found in the wall of the cyst, and markedly disorganized ocular tissue forming a tumor-like mass filled the microphthalmic eyeball. In view of these histopathologic findings I could draw the conclusion that developmental failure of the embryonic eyeball and consequential proliferation of the embryonic neuroepithelial cells occurred at an early developmental stage causing the formation of microphthalmos with cyst.

Retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) in diabetic patients with normal tension were analyzed using optical coherence tomography (OCT), which revealed that diabetes induce morphologic changes in optic disc and RNFL thickness. Methods: A total of 192 patients with type 2 diabetes were analyzed with fundus examination and classified as having normal retina, mild-moderate, severe nonproliferative retinopathy (NPDR), or proliferative retinopathy (PDR). These patients were evaluated with OCT and compared with normal control group. Results: The mean average thickness and nasal average thickness of RNFL in mild-moderate, and severe NPDR groups decreased compared with those of the other groups. There was an increase in the temporal average thickness of RNFL in the PDR group. As the duration of diabetes increased, the mean average and nasal average of RNFL thickness also decreased. The severity of diabetic retinopathy didn't show statistically significant differences in a topographic analysis of the optic nerve head. Conclusions: The mean average thickness and nasal average of RNFL decreased in NPDR groups. Diabetic changes should be considered when diabetes patients are diagnosed with glaucoma or glaucoma progression.