The Use of Goldmann Applanation Tonometer in Intraocular Pressure Measurement of Eyes Wearing Soft Contact Lenses

The purpose of the study was to evaluate a modified technique of Goldmann applanation tonometry without the use of fluorescein and anesthesia in normal eyes with soft contact lenses (SCLs) and to compare this technique with the conventional method. Fifty eyes were measured using Goldmann applanation tonometer. A mean intraocular pressure(IOP)was 17.5 +/-2.33mmHg by the conventional technique and 15.2 +/-2.35 mmHg by the modified technique. We found the IOPvalues of the modified method were consistently underestimated IOP levels by approximately 2.3 mmHg than those of the conventional method (R=0.86, p<0.05). This bias appears to be affected by the fluorescent dye, not affect-ed by the presence of SCL. Our results suggest that the measurements by the modified technique can reflect the IOP measured by conventional method with correction factor of+2 .3 mmHg. The modified technique is a very convenient and simple screening method to measure IOP in patients wearing SCLs, without need for removal or staining of lenses.

Whole Layer Photocoagulation on the Rabbit Retina with Indirect Diode Laser Ophthalmoscopy

In the treatment of retinopathy of prematurity, it is necessary to coagulate retina including inner retinal layer to achieve regression. However, diode laser has long wavelength, thus damage to bruch`s membrane or choroid can occur when one attempts to coagulate whole retinal layers. We evaluated whether or not we could coagulate whole retinal layer without damage to Bruch`s membrane or choroid in rabbit eyes with indirect diode laser ophthalmoscopy. We palaced laser spots on retina of pigmented rabbits with various laser powers(150, 300, 500mW) and durations(0.3, 0.5, 1.0 second). Fundus photographs were taken immediately after photocoagulation. then we took fundus photographs and enucleated the eyes at one day, one week, 3 weeks, and 5 weeks after photocoagulation to perform pathologic examination. With laser setting of 150mW and 0.3 second, the coagulated retina revealed damaged outer layer but inner retinal layer was spared. We could coagulate whole retinal layer without any damage to Bruch`s membrane or choroid with laser power of 300mW and 0.3 second duration. In 300mW, 0.5 second laser burns and 500mW, 0.3 second burns, internal limiting membrane remained intact while Bruch`s membrane and whole retinal layers were damaged We found whole layer rabbit retina could be coagulated without damage to Bruch`s membrane and choriocapillaries with indirect diode laser opthalmoscopy. and we think it would be necessary to adjust laser power and duration in clinical situation to minimize possible deep tissue injury by diode laser.

Two Cases of Isolated Foveal Hypoplasia

Foveal hypoplasia has been described in association with aniridia, albinism, microphthalmia and achromatopsia. Isolated foveal hypoplasia unassociated with other ocular abnormalities has been rarely reported and is regarded as a rare condition. Authors experienced two cases of isolated foveal hypoplasia in the same family. A 30-year-old woman and her 3-year-old daughter presented with a complaint of poor visual acuity and nystagmus. Ophthalmoscopic examination of their both eyes revealed loss of foveal reflex, absence of macular luteal pigment, and abnormal distribution of retinal vessels at the posterior pole. No abnormal ocular findings other than lens opacity, high myopia, and large optic cup were found.

The Effect of Centrally Aligned Image Acquisition on the Reproducibility of Optic Nerve Head Topographic Parameters obtained with Heidelberg Retina Tomograph

To compare the effect of centrally aligned image acquisitions with that of roughly centered image acquisitions on the reproducibility of topographic parameters obtained with the Heidelberg Retina Tomograph. three optic nerve head images were acquired sequentially by the rough centration of live image on the monitor, after then another three images sequentially by the central alignment in five healthy eyes of five subjects. For the centrally aligned image acquisitions, the contour of the frozen live optic nerve head image of each eye was copied into the transparent film. The images were acquired when the margin of live image fitted the contour line on the film. The reliability coefficients of the parameters ranged from 59.4% to 98.2% by the rough centration and 89.7% to 98.7% by the the central alignment. The results indicate that centrally aligned image acquisition provide highly reproducible topographic data of optic nerve head.

The Effect of Holmium:YAG Laser Thermokeratoplasty on Corneal Astigmatism in Rabbits

This animal study was conducted to investigate the effect of holmium:YAG laser thermokeratoplasty on correction of hyperopic astigmatism. A pulsed holmium:YAG laser emitting a wavelength of 2.06 micrometer was used. Arcuate, reverse arcuate, linear patterns of laser burn were applied along the flat corneal meridian and their effects on the rabbit corneal curvature were studied. Keratometric measurements and cycloplegic refractive error were determined preoperatively, one, two, and three months after operation. The changes of refractive astigmatism in three patterns of laser burn were 0.8130, 3.0243, 0.8437 diopter, respectively, compared to that of the control group on postoperative three months. The changes of keratometric astigmatism were 1.1719, 3.0737, 0.7812 diopter, respectively, compared to that of the control group on postoperative three months. We found that holmium:YAG laser thermokeratoplasty is effective in steepening flat corneal meridian, and the most effective pattern is reverse arcuate type. In future holmium:YAG laser thermokeratoplasty might be clinically applicable as a operation of hyperopic astigmatism correction.

Surgical management for stage 5 retinopathy of prematurity

To determine the prognosis of advanced retinopathy of prematurity (ROP) after surgery, we reviewed retrospectively the results of vitrectomy performed between November 1987 and December 1993 in 38 eyes with stage 5 ROP. The patients' mean age at surgery was 11 months, mean follow-up period was 24.1 months. Anatomical success, defined as reattachment of posterior pole retina, was achieved in 11 eyes (29.0%) and functional success, defined as presence of fixation and following was achieved in 7 eyes (18.4%). Anatomical success was well correlated with preoperative configuration of retina, i.e. open-funnel type showed better results than closed-funnel type (44.4% compared to 15.0%). There were no differences between anatomical success and failure group according to gestational age, birth weight, age at the time of diagnosis of ROP, chronological and postconceptional age, and body weight at the time of surgery. For good prognosis, it is necessary to operate early in stage 5 ROP when retinal funnel is still open.

Surgical management for stage 5 retinopathy of prematurity

To determine the prognosis of advanced retinopathy of prematurity (ROP) after surgery, we reviewed retrospectively the results of vitrectomy performed between November 1987 and December 1993 in 38 eyes with stage 5 ROP. The patients' mean age at surgery was 11 months, mean follow-up period was 24.1 months. Anatomical success, defined as reattachment of posterior pole retina, was achieved in 11 eyes (29.0%) and functional success, defined as presence of fixation and following was achieved in 7 eyes (18.4%). Anatomical success was well correlated with preoperative configuration of retina, i.e. open-funnel type showed better results than closed-funnel type (44.4% compared to 15.0%). There were no differences between anatomical success and failure group according to gestational age, birth weight, age at the time of diagnosis of ROP, chronological and postconceptional age, and body weight at the time of surgery. For good prognosis, it is necessary to operate early in stage 5 ROP when retinal funnel is still open.

Silicone oil keratopathy

Light microscopy and electron microscopic examination were carried out on the corneal buttons of two patients who required penetrating keratoplasty for treatment of corneal complication following the intraocular injection of silicone oil to repair recurrent retinal detachments in aphakic eyes. Light microscopic examination demonstrated increased cellularity and irregularity of collagen fibers of stromal layer, defect of endothelial cell layer and endothelial degeneration. Electron microscopy examination demonstrated marked decrease in endothelial cell population density, accompanied by flattening and thinning of the remaining cells and attenuation of cell borders. There were silicone droplets in the endothelial cell layer and collagenous layer posterior to endothelial layer. These findings are well correlated to clinical manifestation and are thought to be rather due to barrier effect of silicone oil than direct toxicity.