Mikio Sasoh

Macular thickness measurements in healthy subjects with different axial lengths using optical coherence tomography.

Purpose To evaluate the retinal thickness of the macula in healthy subjects with different axial lengths. Methods Included were 203 healthy subjects (116 males and 87 females). The axial length of the eyes ranged from 22.68 to 30.22 mm. Four optical coherence tomograms were obtained in a radial spoke pattern centered on the central fovea. Retinal thickness was calculated from the inner and outer retinal boundaries. The average retinal thickness in three circular areas surrounding the central fovea (350, 1,850, and 2,850 &mgr;m in diameter) was determined. Results The retinal thickness in the three circular areas was not significantly correlated with the axial length of the eye (P = 0.10, P = 0.39, and P = 0.12). There also was no statistically significant difference found between the average thickness in emmetropic and low myopic, mildly myopic, and highly myopic eyes in the three circular areas (P = 0.35, P = 0.38, and P = 0.14). Conclusion When eyes with pathologic myopia were excluded, the axial length of the eye was found not to influence the average retinal thickness in the macular area.

Macular buckling for retinal detachment due to macular hole in highly myopic eyes with posterior staphyloma.

Purpose: To evaluate the efficacy of macular buckling surgery using a special exoplant. Methods: The authors reviewed 33 cases of patients with retinal detachment due to macular hole with posterior staphyloma who underwent a macular bucking procedure and 11 cases of patients with the same condition due to macular hole without posterior staphyloma or due to a hole along the edge of the posterior staphyloma who underwent gas injection or vitrectomy. The reattachment rate, visual acuity (VA). and area size (V‐4,1‐4 isopter) by Goldmann perimetry were calculated. Results: Reattachment rate for the macular buckling procedure was 94% (initial) and 100% (final), and that for the gas injection or vitrectomy was 100% (both initial and final). Twenty of the 33 eyes (60.6%) had VA of 20/400 or better, and none of these 33 eyes had a VA at the level of finger counting or poorer following macular buckling. Nine of the 11 eyes (81.8%) had VA of 20/400 or better, and none of these 11 eyes had a VA at the level of finger counting or poorer following the gas injection or vitrectomy. The area size of V‐4 isopter in the macular buckling group was significantly larger than that in the gas injection or vitrectomy group (P = 0.017). Conclusion: The macular buckling procedure is effective when considered both from an anatomic and a functional perspective for retinal detachment due to macular hole with posterior staphyloma.

Retinal Nerve Fiber Layer Decrease during Glycemic Control in Type 2 Diabetes.

Purpose. To assess an effect of glycemic control on retinal nerve fiber layer (RNFL) in type 2 diabetes mellitus. Methods. Thirty-eight eyes of 38 patients with type 2 diabetes undergoing blood glucose regulation were enrolled. All patients were examined at (1) initial visit, (2) 1 month, (3) 2 months, and (4) 4-month after the initial examination. On each occasion, glycosylated hemoglobin (HbA1c) levels and optical coherence tomography (OCT) scanning for RNFL thickness were evaluated. 360 degree circular OCT scans with a diameter of 3.4 mm centered on the optic disc were performed. Results. Significant RNFL decrease was seen in the superior area between initial and 4 months examination (P = .043). The relationship between the changes in HbA1c and the changes in RNFL thickness was observed in superior, temporal, and inferior area (P < .05) at 4 months. Conclusions. This study suggests that the glycemic control affects RNFL within 4 months.

Extrusion and fragmentation of hydrogel exoplant 11 years after scleral buckling surgery

MAI or MIRAgel is a hydrogel developed as a scleral buckling material. We identified upper lid masses and a limitation of supraduction in the left eye of a patient who was associated with extrusion and fragmentation of the MIRAgel episcleral exoplant 11 years after scleral buckling surgery. The material could not be removed completely because of fragmentation. Fragmentation and extrusion of MIRAgel may be rare, but periodic long-term follow-up examinations should be performed after this product has been used.

Diode laser endophotocoagulation

Purpose: To evaluate the utility, safety, and reliability of diode laser endophotocoagulation in a sizable clinical series. Methods: Two hundred twenty‐six consecutive eyes treated with diode endophotocoagulation were studied prospectively. Surgical indications included proliferative diabetic retinopathy (134 eyes), proliferative vitreoretinopathy (27 eyes), complicated retinal detachment (50 eyes), and miscellaneous (15 eyes). A retrospective comparison group of 67 consecutive eyes undergoing vitrectomy with argon endolaser photocoagulation was also studied. Results: The desired intraoperative effect of diode endophotocoagulation was achieved in 99.6% cases without complication. Final visual acuity was improved in 159 eyes (71%), and was 5/200 or better in 157 eyes (70%) with diode endophotocoagulation. In comparison, final visual acuity was improved in 48 eyes (73%), and was 5/200 or better in 45 eyes (68%) for argon endophotocoagulation. No statistically significant difference was found between the two groups regarding rate of visual improvement or final visual results. Conclusion: This series supports the conclusion that the diode laser is as safe, reliable, and effective for endophotocoagulation as argon treatment.

Anterior chamber structural change in postural variation in pseudoexfoliation syndrome

PURPOSE The anterior chamber structure in the supine position and the prone position was investigated with ultrasound biomicroscopy (UBM) in pseudoexfoliation syndrome (PE). METHODS We studied 12 eyes of 12 PE subjects. Patients were placed in the supine position for 30 minutes, after which UBM was performed. The UBM was repeated after 30 minutes in the prone position. Anterior chamber depth (ACD), angle opening distance 500 microns (AOD 500), and angle recess area (ARA) in 4 quadrants were measured. RESULTS Following the postural change from the supine position to the prone position, ACD decreased significantly (p < 0.0001). AOD 500 and ARA decreased significantly in the superior (AOD 500: p < 0.05, ARA: p = 0.03) and temporal quadrants (AOD 500: p < 0.0001, ARA: p < 0.0001). CONCLUSIONS The anterior chamber structural change was greater in the temporal and superior quadrants in the PE eyes. This corresponds with previous reports that zonular involvement by pseudoexfoliation material is more pronounced temporally and superiorly.

Infrared measurement of thermal constants in laser-irradiated scleral tissue

Laser scleral buckling (LSB) experiments were performed by irradiating human cadaver eyes with a focused beam from a 2.1-micrometer Ho:YAG laser. Spatially and temporally resolved temperature maps of the sclera were inferred from infrared images of the tissues thermal radiation. An infrared focal-plane camera operating in the 3- to 5-micrometer wavelength interval was used for the measurements, from which we derived absorption and thermal diffusivity coefficients of the scleral tissue, along with the temperature dependence of these coefficients. A thermal-response model was developed, which describes the tissue surface temperature in response to a train of laser pulses, given the pulse repetition rate, beam fluence, spot size, and total energy delivered. This model provides guidance for optimization of laser-irradiation parameters for LSB treatment.

Quantification of Holmium:YAG and Thulium:YAG Laser-Induced Scleral Shrinkage for Buckling Procedures

BACKGROUND AND OBJECTIVE To quantify and compare holmium:YAG (2.1 microns) and thulium:YAG (2.0 microns) laser-induced scleral shrinkage for retinal buckling procedures. MATERIALS AND METHODS Two overlapping spots of either laser radiation were applied at the equatorial sclera of 50 human cadaver eyes. Scleral shrinkage was expressed as a relative change of length between two reference points on the scleral surface, and quantified as a function of energy per pulse, total energy, scleral thickness, and intraocular pressure (IOP). Tissue effects were studied histopathologically. RESULTS Shrinkage was most dependent on total fluence and attained a maximum of 27% to 30% with an IOP of 4 mm Hg, regardless of scleral thickness or laser parameters, but decreased with increasing IOP. The thulium:YAG laser produced more efficient scleral shrinkage and less collagen damage than the holmium:YAG laser. CONCLUSION The recommended parameters for laser-induced scleral shrinkage are the thulium:YAG laser, with 2.4 J/cm2 per pulse and 12.0 to 14.4 J/cm2 total fluence (5 to 6 pulses). IOP control (< or = 4 mm Hg) is crucial during laser scleral buckling.

Retinal detachment because of macular hole and an additional break within the staphyloma.

PURPOSE To report the finding of retinal detachment because of macular hole and an additional break within the posterior staphyloma. METHODS A 63-year-old woman presented with progressive central scotoma of the right eye for 1-month duration. The fundus in the right eye showed retinal detachment that was localized within the posterior staphyloma and macular hole. An additional retinal break was observed within the staphyloma using ophthalmoscope, and optical coherence tomography confirmed that both the breaks were within the staphyloma. Macular buckling was scheduled because the two breaks were close enough to each other and the patient was unable to maintain a prone position. RESULTS The retinal detachment was successfully reattached using macular buckling procedure. CONCLUSION In the present case, optical coherence tomography proved to be very useful in helping to make the correct diagnosis of a full-thickness break before surgery.

Experimental intraocular laser surgery with a GRIN laser endoscope

Endoscopy is a method of observation that allows direct viewing of certain internal structures of the eye which cannot be easily visualized through conventional slit lamp/microscope arrangements. An endoscopic system can also be helpful when a transparent structure of the eye becomes turbid, e.g., a hazy cornea. Over the past years substantial efforts have been oriented to miniaturize endoscopes for use in ophthalmology. Ophthalmic endoscopes have been presented on the basis either of coherently ordered fiber bundles or of optical lenses such as the gradient-index ones (GRIN). Endoscopes that provide a basic visualization function can also be fitted with one or more ancillary channels that may provide additional features such as aspiration/injection or laser treatment.