R. Koide

Intraocular lens power calculation for microphthalmos

Purpose: To evaluate the refractive results and accuracy of intraocular lens (IOL) power calculation formulas in eyes with microphthalmos. Setting: Department of Ophthalmology, Showa University Hospital, Tokyo, Japan. Methods: The accuracy of IOL power calculated using the SRK, SRK II, S‐SRK, SRK/T, Holladay, and Hoffer Q formulas was evaluated in six eyes with axial lengths less than 19.0 mm. Results: Postoperative measurement of refraction showed a tendency toward hypermetropia compared with the refraction predicted by each formula. The best predicted refraction was calculated using the SRK/T formula. The tendency for hyperopic estimation was related to the axial length, particularly in eyes with a shorter axial length. However, there was no relationship between the refractive power of the cornea and the error in the predicted refraction by the SRK/T formula. Two eyes with an IOL power of 30.0 diopters (D) had severe hypermetropia. Conclusion: Theoretical formulas were more accurate than empirical ones in eyes with microphthalmos. The severe hypermetropia in the two eyes with a 30.0 D IOL indicates that such patients require a higher IOL power.

Retinal hazard from blue light emitting diode

PURPOSE To compare the effect of exposure time from a blue(460 nm) light emitting diode(LED) on the morphology of the outer retina and determine conditions where damage occurs. MATERIALS AND METHODS Young adult rhesus monkeys were anesthetized, and received blue LED exposure from a modified slit-lamp. A 3 mm beam of 0.85 mW was imaged onto the retina through a lens positioned before the cornea and exposure damage was determined at time intervals for 12 to 90 min. Fundus photography, fluorescein angiography(FAG), retinal tomography(HRT), and s-cone electororetinogram(S-ERG) were recorded at baseline, 2, and 30 days. RESULTS Two days after 40 min exposure, there was a grey, discolored region, which was over-fluorescent in FAG, and an incresse in HRT and S-ERG corresponding to the site which was exposed to LED light. In histological examination at 30 days, the LED had caused produced a marked disruption of the disks of photoreceptor cells, damaged retinal pigment epithelium(RPE) apical villi, and a loss of RPE melanin after 90 min exposure. CONCLUSION A threshold level was found around 40 min. This morphological damage may impair function and continuous exposure to blue light is potentially dangerous to vision.

Accuracy of Intraocular Power Calculation Formulas

PURPOSE We examined the accuracy of intraocular lens power calculation formulas, with special emphasis on the prediction of refraction in different axial lengths. MATERIAL AND METHODS 786 cases were subdivided into four groups based on the axial length (short axial length < 22.0 mm, normal axial length = 22-24.4 mm, mid-range axial length = 24.5-26.9 mm and long axial length > 27 mm). Seven different formulas (Holladay, SRK, SRK II, SRK/T, S-SRK, M-SRK, L-SRK) were tested for their accuracy in predicting post-operative refraction. RESULT The best results were obtained using the S-SRK formula in the short axial length group (n = 114), The SRK and Holladay formulas in the normal axial length group (n = 278). The Holladay and SRK/T formulas in the mid-range axial length group (n = 135), and the SRK/T and L-SRK in the long axial length group (n = 259). CONCLUSION Our results emphasize the importance of using an intraocular lens formula specific for each range of axial length when calculating the predicted refraction.

Analysis of preoperative factors predictive of visual acuity in axial myopia

Purpose: To identify the factors predicting visual acuity after cataract surgery in patients with high myopia. Setting: Departments of Ophthalmology, Showa University School of Medicine and Showa University Fujigaoka Hospital, Kanagawa, Japan. Methods: Stepwise regression analysis was used to identify the factors determining the visuai acuity in 940 eyes with an axial length of 27.0 mm or longer having cataract surgery. Using a formula derived from the stepwise regression analysis, the predicted postoperative visual acuity was compared with the actual value measured in another group of 104 eyes. Results: Five factors were identified to significantly determine postoperative visual acuity axial length, age, corneal opacity, refractive power of the cornea, and history of retinal detachment surgery. There was a significant relationship between predicted and actual postoperative visual acuities (r= .51, P < .001). Postoperative visual acuity was similar in 63% of cases. Conclusion: The results showed that at least five factors determine visual acuity after cataract surgery in patients with high‐myopia.

Kinetic magnetic resonance imaging of orbital blow-out fracture with restricted ocular movement

We investigated the mechanisms of restricted eye movement using animated MRJ pictures in 19 cases of blow-out fracture examined on day one to 15 months after injury. A shadow of connective tissue septa (referred to below as septa) was distinctly confirmed in or towards the prolapsed adipose tissue in I I cases. Even in those patients with a larger deviation of the external ocular muscle, the muscle was almost entirely surrounded by adipose tissue and no patient had incarcerated muscle directly into the fractured site. Our results indicate that incarceration of the septa limited the movement of the external ocular muscle. Incarceration of septa also limited the movement of the optic nerve in some patients, suggesting that abnormalities in optic nerve movement may also contribute to the dyskinesia of the eyeball. The use of animated MRI in our analysis suggests that the presence of incarcerated septa is the main cause of restricted eye movement in blow-out fractures. Specifically, we confirmed that incarcer...

Accumulation of 14C-cystine in inherited cataractous rat lens

This study was designed to investigate the formation of mixed disulfides of protein and glutathione (GSH) in the cataractous lens. We compared the changes in accumulation of 14C-cystine in cultured inherited cataractous rat lens (ICR/f) during cataractogensis with those in Wistar strain rats. The accumulation of 14C-cystine in water insoluble protein (WIP) of the lens was increased, especially in lens recognized cataract. The radioactivity accumulated in the WIP was released by incubation with 2-mercaptoethanol (2-ME), dithiothereitol (DTT) and GSH. The accumulation of 14C-cystine in WIP was inhibited by pretreatment with DTT. The existence of some materials in the lens-which combined with S-S compounds became clear. A large part of the materials is present in WIP which is increased along with the lens opacification. We surmised that the accumulation of 14C-cystine was related to the reaction of protein-glutathione disulfide (PSSG).