Published papers

We newly developed a Point Spread Function Analysis System (PSFAS) to study the optical system of the human eye. In this system, an infrared point light source is projected onto the subject's eye and the reflected image at the retina is captured by the charge coupled device (CCD) (i.e., double-pass formula). The single-pass modulation transfer function (MTF) is calculated from the captured image with equal sized apertures of the entrance and exit pupils, and the phase transfer function (PTF) is calculated from the captured image with unequal sized apertures of them. The optical transfer function (OTF) is deduced from this MTF and PTF, then retinal images can be simulated with both this OTF and the original charts. The smaller aperture of the incident ray is determined so as to give a diffraction limit, then the simulated retinal images include the information of asymmetric aberrations. The simulated retinal images of the Landolt's rings were compared with subjective sensations in the same subject with keratoconus. The PSFAS can objectively evaluate the characteristics of the human optical system and therefore is very useful in an ophthalmology clinic setting.

We report 3 cases of 3 eyes in which conjunctival reconstructive surgery was performed as treatment for epiphora caused by conjunctivochalasis. Case 1, a 58-year-old male with a previous history of surgeries for pterygium, came to our clinic complaining of epiphora in his right eye. Case 2, a 51-year-old female, began to complain of epiphora in her right eye after trabeculectomy. Case 3, a 70-year-old male, diagnosed as having allergic conjunctivitis, complained of epiphora even after relief from conjunctivitis. All had neither malposition of the lacrimal puncta or eyelid, nor inflammation or tumor of the lacrimal system. Nor had they any disease that could cause overproduction of tears. Drainage of the lacrimal system was normal, with easy passage to the nose, but conjunctivochalasis was found around the inferior puncta in all cases. Following surgical resection and reconstruction of the redundant conjunctiva, the symptoms of epiphora disappeared. Conjunctivochalasis is important as a cause of epiphora; reconstructive surgery for redundant conjunctiva may be useful in relieving the symptom.

PURPOSE: To determine the clinical usefulness of a five-zone refractive multifocal intraocular lens. METHODS: After more than 1 year of follow-up, we evaluated the visual function of 22 patients (36 eyes) who had received the MPC 25NB intraocular tens for distance and near visual acuity, kinetic visual acuity, and near contrast sensitivity, and for patient satisfaction. RESULTS: Of 31 study eyes with less than 1.5 diopters of preoperative keratometric astigmatism, 28 (90.3%) achieved an uncorrected distance visual acuity of 20/40 or better; best-corrected distance visual acuity was 20/20 or better in 31 (86.1%) of 36 eyes. Near visual acuity with distance correction was 20/40 or better in 20 (60.6%) of 33 eyes. Kinetic visual acuity in these patients was comparable to that in patients with monofocal intraocular lenses. Distance visual acuity and near contrast sensitivity were below normal or within the low normal range. There was no significant difference in contrast visual acuity measured by variable contrast visual acuity charts between MPC- 25NB and monofocal intraocular lens-implanted eyes (P > .05). Four (22.2%) of 18 patients did not require spectacles when the intraocular lens was implanted for emmetropia. Despite some complaints about near or night vision, all patients expressed satisfaction. CONCLUSIONS: The MPC-25NB lens provides a level of distance vision comparable to that of a monofocal intraocular lens and a useful level of near visual acuity without spectacles. However, we should carefully evaluate the indication for use of MPC-25NB in patients who require good near vision or night vision.

We measured the strength of haptics of two types of intraocular lens (IOL) made by Nidek Co. One has equal haptics in diameter (NR-84C) and the other unequal ones (NR-84K). We used a digital force guage to which the optics of each IOL was fixed. The end of haptics was pulled either parallel or vertical to the optics at the speed of 40 mm/min. We recorded the strength of the force at the break point of the haptics. When the power was applied parallel to the optics, the breaking power was significantly less for NR-84K than NR-84C (p < 0.05). The haptics broke at their end for either type of IOL. When the power was applied vertical to the optics, the breaking power was the same for both types of IOL. The haptics broke at the end of haptics for NR-84K and near the root for NR-84C. The findings show that haptics unequal in diameter are weaker than those with equal ones. Standardization in the strength of haptics is desired in order to avoid their break during transscleral fixation of IOL.

Purpose: To determine the incidence of Elschnig pearl formation along the capsulotomy margin (string of pearls) after neodymium:YAG (Nd:YAG) laser posterior capsulotomy and to elucidate its clinical features, predisposing factors, effect on visual function, and association with additional capsulotomy. Setting: Keio University Hospital, Tokyo, Japan. Methods: The records of 418 eyes that had Nd:YAG posterior capsulotomy after cataract surgery were retrospectively reviewed. Of those, 315 were excluded for short follow-up (fewer than 12 months) or insufficient clinical examination data. In the remaining 103 eyes, the incidence of string of pearls was calculated, and its clinical features, predisposing factors, effect on visual function, and correlation with additional capsulotomy were evaluated. Results: String of pearls was identified in 49 eyes (47.6%); 37 (75.5%) developed pearls within 1 year after Nd:YAG capsulotomy. The incidence was significantly higher in patients having intraocular lens implantation and continuous curvilinear capsulorhexis (CCC) than in those without (95.9 versus 61.1% and 97.9 versus 55.6%, respectively). No significant differences were found in patient age and sex, total Nd:YAG energy, and the presence of diabetes mellitus or high myopia. String of pearls caused visual disturbances in 17 eyes (34.7%). The rate of repeat capsulotomy was higher in patients with string of pearls than in those without (36.7 and 9.3%, respectively). Conclusions: String of pearls formation was a common and significant complication after Nd:YAG posterior capsulotomy. Intraocular lens implantation and CCC may promote its formation.

PURPOSE: To determine the incidence of Elschnig pearl formation along the capsulotomy margin (string of pearls) after neodymium:YAG (Nd:YAG) laser posterior capsulotomy and to elucidate its clinical features, predisposing factors, effect on visual function, and association with additional capsulotomy. SETTING: Keio University Hospital, Tokyo, Japan. METHODS: The records of 418 eyes that had had Nd:YAG posterior capsulotomy after cataract surgery were retrospectively reviewed. Of those, 315 were excluded for short follow-up (fewer than 12 months) or insufficient clinical examination data. In the remaining 103 eyes, the incidence of string of pearls was calculated, and its clinical features, predisposing factors, effect on visual function, and correlation with additional capsulotomy were evaluated. RESULTS: String of pearls was identified in 49 eyes (47.6%); 37 (75.5%) developed pearls within 1 year after Nd:YAG capsulotomy. The incidence was significantly higher in patients having intraocular lens implantation and continuous curvilinear capsulorhexis (CCC) than in those without (95.9 versus 61.1% and 97.9 versus 55.6%, respectively). No significant differences were found in patient age and sex, total Nd:YAG energy, and the presence of diabetes mellitus or high myopia. String of pearls caused visual disturbances in 17 eyes (34.7%). The rate of repeat capsulotomy was higher in patients with string of pearls than in those without (36.7 and 9.3%, respectively). CONCLUSIONS: String of pearls formation was a common and significant complication after Nd:YAG posterior capsulotomy. Intraocular lens implantation and CCC may promote its formation.

PURPOSE: To determine the clinical usefulness of a five-zone refractive multifocal intraocular lens. METHODS: After more than 1 year of follow-up, we evaluated the visual function of 22 patients (36 eyes) who had received the MPC-25NB intraocular lens for distance and near visual acuity, kinetic visual acuity, and near contrast sensitivity, and for patient satisfaction. RESULTS: Of 31 study eyes with less than 1.5 diopters of preoperative keratometric astigmatism, 28 (90.3%) achieved an uncorrected distance visual acuity of 20/40 or better; best-corrected distance visual acuity was 20/20 or better in 31 (86.1%) of 36 eyes. Near visual acuity with distance correction was 20/40 or better in 20 (60.6%) of 33 eyes. Kinetic visual acuity in these patients was comparable to that in patients with monofocal intraocular lenses. Distance visual acuity and near contrast sensitivity were below normal or within the low normal range. There was no significant difference in contrast visual acuity measured by variable contrast visual acuity charts between MPC-25NB and monofocal intraocular lens-implanted eyes (P > .05). Four (22.2%) of 18 patients did not require spectacles when the intraocular lens was implanted for emmetropia. Despite some complaints about near or night vision, all patients expressed satisfaction. CONCLUSIONS: The MPC-25NB lens provides a level of distance vision comparable to that of a monofocal intraocular lens and a useful level of near visual acuity without spectacles. However, we should carefully evaluate the indication for use of MPC-25NB in patients who require good near vision or night vision.