Mihori Kita

Poly(vinyl alcohol) hydrogels as soft contact lens material

A new type of soft contact lens was developed from the poly(vinyl alcohol) (PVA) hydrogel prepared by a low temperature crystallization technique using a water-dimethyl sulfoxide mixed solvent. The PVA contact lens materials had a water content of 78% and a tensile strength of 50 kg/cm2, five times as strong as that of commercial poly(2-hydroxyethyl methacrylate) soft contact lens. The amount of proteins adsorbed to the PVA soft hydrogel material was half to one thirtieth of that of conventional soft contact lenses. Histological and scanning electron microscopic observation of rabbit eyes which had worn the PVA soft contact lens for 12 weeks showed no difference in corneal epithelium and cell arrangement in the corneal epithelium from the non-wearing eyes.

Association between integrity of foveal photoreceptor layer and visual acuity in branch retinal vein occlusion

Aim: To study the correlation between integrity of the photoreceptor layer after resolution of macular oedema (MO) associated with branch retinal vein occlusion (BRVO) and final visual acuity (VA), and to determine prognostic factors for visual outcome. Methods: We retrospectively studied 46 eyes from 46 patients with resolved MO secondary to BRVO, the foveal thickness of which was less than 250 µm at final observation. We assessed the status of the third high reflectance band (HRB) in the fovea using optical coherence tomography (OCT) at final observation, and studied OCT images taken at the initial visit in the hope of identifying a factor that would be prognostic of visual outcome. Results: No differences were found in initial VA or in foveal thickness between eyes with or without complete third HRB at final observation. However, final VA in eyes without a complete HRB was significantly poorer (p<0.002). Additionally, initial status of the third HRB in the parafoveal area of unaffected retina was associated with final VA; lack of visualisation of the third HRB at 500 µm (p = 0.0104) or 1000 µm (p = 0.0167) from the fovea on initial OCT images was associated with poor visual recovery after resolution of the MO. Conclusion: Integrity of the photoreceptor layer in the fovea is associated with VA in resolved MO, and status of the third HRB before treatment might be predictive of visual outcome.

Integrity of foveal photoreceptor layer in central retinal vein occlusion.

Purpose: To study the correlation between final visual acuity and integrity of the foveal photoreceptor layer after resolution of macular edema (ME) associated with central retinal vein occlusion (CRVO). Methods: We studied retrospectively 27 eyes of 27 patients with resolved ME associated with central retinal vein occlusion. On optical coherence tomography, integrity of the foveal photoreceptor layer was studied using the junctions between inner and outer segments of the photoreceptor (IS/OS) line as a hallmark. Results: At the final visit, foveal thickness was decreased to a physiologic level in all eyes. On optical coherence tomography, 14 eyes showed the IS/OS line in the fovea, whereas 13 eyes showed no IS/OS line. In concordance with resolution of the ME, visual acuity had improved significantly by the final visit. However, final visual acuity in eyes without an IS/OS line was significantly poorer than that in eyes with an IS/OS line (P < 0.0001). In addition, integrity of the foveal photoreceptor layer after resolution of the ME had a significant correlation with the initial retinal perfusion status (P = 0.0156) and with initial visual acuity (P = 0.0050). Conclusions: After resolution of the ME associated with central retinal vein occlusion, visual acuity is closely associated with integrity of the foveal photoreceptor layer.

Serous Retinal Detachment Associated With Retinal Vein Occlusion

PURPOSE To study the pathomorphology of serous retinal detachment (RD) associated with retinal vein occlusion by optical coherence tomography (OCT). DESIGN Retrospective chart review. METHODS Ninety-one eyes of 91 patients with macular edema associated with retinal vein occlusion had undergone a comprehensive ophthalmologic examination, including measurement by spectral-domain OCT. RESULTS Eyes with macular edema associated with retinal vein occlusion typically showed foveal cystoid spaces and marked retinal swelling, especially in the outer retina. In addition, 76 eyes (83.5%) showed serous RD involving the fovea, which ranged in thickness from 64 microm to 871 microm (219.2 +/- 161.6 microm). Fifty-two eyes showed a small pointed RD, with a small base. The point of the RD was always located beneath the fovea, where the outer surface of the swollen neurosensory retina seemed to be contracted inward, resulting in development of the pointed RD. Two eyes with no RD at the initial visit developed such a pointed RD during follow-up. In contrast, 24 eyes showed a more dome-shaped RD, with a large base, and in 18 eyes, a pointed RD seen at the initial visit changed into a dome-shaped RD during follow-up. In some cases, small outer retinal discontinuity was seen on the external surface of the swollen neurosensory retina. CONCLUSIONS In eyes with retinal vein occlusion, a small pointed RD initially developed just beneath the fovea, but subsequently changed into a dome-shaped RD. Based on the findings by OCT, we hypothesize that the foveal architecture, especially that of the Müller cell cone, is involved in the formation of serous RD.

Comparison of the Effect of Ranibizumab and Verteporfin for Polypoidal Choroidal Vasculopathy: 12-Month LAPTOP Study Results

PURPOSE To compare the effect of photodynamic therapy (PDT) and intravitreal ranibizumab in patients with polypoidal choroidal vasculopathy (PCV). DESIGN Randomized clinical trial. METHODS SETTING Multicenter. STUDY POPULATION Total of 93 patients with treatment-naïve PCV. INTERVENTION Patients were randomized to 2 arms. Patients in the PDT arm underwent a single session of PDT with verteporfin, and patients in the ranibizumab arm received 3 monthly ranibizumab injections at baseline. Additional treatment was performed as needed in each arm. MAIN OUTCOME MEASURES Primary outcome measurement was the proportion of patients gaining or losing more than 0.2 logarithm of minimal angle of resolution (logMAR) units from baseline. Mean change of logMAR and central retinal thickness (CRT) were also evaluated. RESULTS In the PDT arm (n = 47), 17.0% achieved visual acuity gain, 55.3% had no change, and 27.7% experienced visual acuity loss. The results were 30.4%, 60.9%, and 8.7%, respectively, in the ranibizumab arm (n = 46), significantly better than the PDT arm (P = .039). In the PDT arm, mean CRT improved (366.8 ± 113.6 μm to 289.1 ± 202.3 μm, P < .001), but logMAR was unchanged (0.57 ± 0.31 to 0.62 ± 0.40). The ranibizumab arm demonstrated improvement in both CRT (418.9 ± 168.6 μm to 311.2 ± 146.9 μm, P < .001) and logMAR (0.48 ± 0.27 to 0.39 ± 0.26, P = .003). Mean change of logMAR was also greater in the ranibizumab arm (P = .011). CONCLUSION Intravitreal injection of ranibizumab is more effective than PDT for treatment-naïve PCV.

Pars plana vitrectomy for cystoid macular edema secondary to sarcoid uveitis.

OBJECTIVE To examine the results of pars plana vitrectomy for cystoid macular edema secondary to sarcoid uveitis resistant to medical treatment. DESIGN Retrospective, interventional, noncomparative case series. SUBJECTS Fourteen consecutive subjects (18 eyes) with cystoid macular edema associated with sarcoid uveitis resistant to medical treatment. INTERVENTION All eyes underwent pars plana vitrectomy. Nine eyes also underwent peeling of the epiretinal membrane or removal of the posterior vitreous cortex. MAIN OUTCOME MEASURES Status of macular edema, visual acuity, and complications. RESULTS Ten eyes (56%) improved 2 or more lines of Snellen visual acuity within 12 months. Six eyes (33%) remained unchanged, within a line of preoperative Snellen visual acuity, and two eyes (11%) worsened by 2 or more lines of Snellen visual acuity. Slit-lamp biomicroscopy showed that cystoid macular edema had resolved in 14 eyes (78%) within 9 months postoperatively. One eye (6%) had minimal edema, whereas three eyes (17%) remained unchanged biomicroscopically at the final visit. Postoperative complications included cataract formation, glaucoma, optic nerve atrophy, epiretinal membrane formation, and tractional retinal detachment. No severe postoperative inflammation was noted. CONCLUSIONS Pars plana vitrectomy seems to have a beneficial effect on cystoid macular edema caused by sarcoidosis resistant to medical treatment.

Spectral-domain optical coherence tomography imaging of the detached macula in rhegmatogenous retinal detachment.

Purpose: To assess detached macula in rhegmatogenous retinal detachment by using spectral-domain optical coherence tomography. Methods: This retrospective study included 15 eyes of 15 patients with macula-off rhegmatogenous retinal detachment and 16 eyes of 16 patients with acute central serous chorioretinopathy. These patients were examined with a prototype spectral-domain optical coherence tomography system. Results: Spectral-domain optical coherence tomography of eyes with rhegmatogenous retinal detachment revealed macular structural abnormalities, such as small cystoid cavities in the inner nuclear layer (2/15 eyes, 13%), cystoid and/or diffuse edema in the outer nuclear layer (10/15 eyes, 67%), undulations of the photoreceptor layer (7/15 eyes, 47%), and dropout of the photoreceptor inner and outer segment layers in the fovea (6/15 eyes, 40%); such changes were not seen in eyes with acute central serous chorioretinopathy. The dropout of foveal photoreceptor inner and outer segment layers was correlated with preoperative and postoperative visual acuities (rs = 0.78, P < 0.005 and rs = 0.63, P < 0.05, respectively), thickness of the outer nuclear layer at the fovea (rs = −0.69, P < 0.01), and height of the retinal detachment at the fovea (rs = 0.60, P < 0.05). Conclusion: Dropout of the foveal photoreceptor inner and outer segment layers seen on spectral-domain optical coherence tomography imaging may be involved in incomplete recovery of visual acuity after successful retinal reattachment surgery.

Prognostic Factor Analysis in Pars Plana Vitrectomy for Retinal Detachment Attributable to Macular Hole in High Myopia: A Multicenter Study

PURPOSE To detect the prognostic factors associated with initial reattachment after primary pars plana vitrectomy (PPV) with gas tamponade for retinal detachment attributable to macular hole (MHRD). DESIGN Retrospective, multicenter, interventional case series. METHODS This study included 49 eyes of 48 patients with MHRD in high myopia (axial length more than 28.0 mm). All eyes underwent PPV with gas tamponade. We retrospectively reviewed the medical records and performed univariate analysis to detect the presence of any difference between eyes with a successful initial reattachment and those that failed. We performed multivariate logistic regression analysis to assess the influence of each preoperative factor on initial success. RESULTS Success rate of initial reattachment was 69%. Postoperative best-corrected visual acuity (BCVA) of 34 eyes with initial success was significantly better than those of 15 eyes with initial failure (P < .05); preoperative BCVA was not significantly different (P = .43). The axial length of eyes with initial success (29.26 +/- 0.94 mm) was shorter than that of eyes with initial failure (30.04 +/- 1.49 mm) with borderline significance (P = .049). There were no significant differences noted for other factors such as use of ILM peeling (P = .43) or type of tamponade gas (P = .99). Multiple logistic regression analysis using preoperative factors indicated that only axial length was significantly associated with initial success (odds ratio, 0.49; 95% confidence interval, 0.26 to 0.93; P < .05). CONCLUSIONS Initial reattachment is important for visual prognosis, and axial length is a prognostic factor for initial reattachment after PPV with gas tamponade for MHRD in high myopia.

Retinal structural changes associated with retinal arterial macroaneurysm examined with optical coherence tomography.

Purpose: To study the retinal structural changes associated with a retinal arterial macroaneurysm and their association with visual prognosis. Methods: We studied retrospectively the medical records of 44 eyes of 44 patients with a retinal arterial macroaneurysm; all eyes showed hemorrhagic and/or exudative changes of the fovea with a visual disturbance. The retinal structural changes were examined by optical coherence tomography (OCT). Results: At the initial visit, 30 eyes (68%) showed severe hemorrhagic complications. In eyes with subretinal hemorrhage beneath the fovea, retinal structure was relatively preserved at the initial visit. At the final visit, however, foveal structure was often degenerated, especially in its outer aspect, with limited visual recovery. The 14 eyes (32%) with minimal hemorrhagic complications showed an extensive exudative change caused by the aneurysm. In 13 of these eyes, OCT examination revealed extensive retinal edema, predominantly in the outer retina. Retinal edema beneath the fovea caused a focal serous retinal detachment in 12 eyes. Eight eyes with extensive exudative change showed an accumulation of hard exudates in the macular area, and visual recovery of these eyes was often limited. Conclusion: Subretinal hemorrhage or extensive exudative change from a retinal arterial macroaneurysm can cause destruction of the foveal outer photoreceptor layer, resulting in a poor visual outcome.

Evaluation of polyvinyl alcohol hydrogel as a soft contact lens material

We prepared a transparent polyvinyl alcohol (PVA) hydrogel from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent by cooling. The physical properties of the hydrogel were evaluated in various mixed solvents and compared with those of commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methylmethycrylate (MMA) and N-vinyl pyrrolidone (N-VP). The PVA hydrogel showed higher tensile strength and elongation before breaking than did the other materials. Also, the PVA hydrogel was comparable in its high water content and its oxygen permeability with the MMA/VP copolymers. The protein adsorption of the PVA hydrogel was much lower than that of the other materials. Soft contact lenses of PVA hydrogel were applied to rabbit eyes for 12 weeks. The effects of the lenses on the cornea were studied by biomicroscopy, ultrasonic pachymetry, and histopathologic examination. No abnormal findings were noted, suggesting that the PVA hydrogel may be promising as a new material for use in soft contact lenses.