Effect of cataract on automated perimetry.

Humphrey visual fields (30-2 program) were performed on 24 otherwise healthy patients before and after cataract extraction to examine the effect of cataract on automated visual fields. All patients met reliability index criteria and recovered visual acuity of 20/25 or better. The effect of learning associated with repeated testing was controlled with visual fields of the fellow eye. Although a greater absolute threshold recovery occurred in the central region of the visual field after cataract extraction, the percent of threshold recovery did not vary across the visual field except for the most peripheral testing points, which demonstrated less recovery. Thus, cataracts depress an automated visual field fairly uniformly. Clinical grading of cataracts by a single experienced clinician was generally a poor predictor of visual field loss. Only the presence of posterior subcapsular plaque in the visual axis and the preoperative visual acuity correlated significantly with postoperative central threshold recovery. Pattern standard deviation remained unchanged after cataract removal, confirming it as a useful way of estimating visual loss from cataracts.

Electroretinography in central retinal vein occlusion. Correlation of electroretinographic changes with pupillary abnormalities.

In 149 eyes with central retinal vein occlusion (CRVO), we prospectively investigated the role of routine, clinical electroretinography (ERG) in differentiating ischemic (60 eyes) from nonischemic CRVO (89 eyes). Single-flash photopic and scotopic ERGs were recorded. Data for the amplitudes and implicit times of a- and b-waves and for the b-/a-wave amplitude ratio were analyzed in detail. The study revealed that the best ERG parameter (for both photopic and scotopic ERG) for differentiating ischemic from nonischemic CRVO was a subnormal b-wave amplitude (reduced to less than or equal to 60% or by greater than or equal to 1 SD from the normal mean value, or less than or equal to 64%-69% of that in the fellow normal eye), with a sensitivity of 80%-90% and a specificity of 70%-80%. ERG findings were correlated with the relative afferent pupillary defect (RAPD). An RAPD of greater than or equal to 0.7 log units showed a sensitivity of 88% and a specificity of 90% in differentiating ischemic from nonischemic CRVO. ERG and RAPD findings showed a good correlation. The combined ERG and RAPD tests could differentiate 97%-100% of ischemic from nonischemic CRVO cases, with a specificity of about 70%.

Neutralization at infinity in streak retinoscopy.

A new principle of retinoscopy proposes that the endpoint of neutralization be placed at infinity rather than into the aperture of the retinoscope. The advantages of the method are (1) the pupillary reflex is sharply defined and enhanced at neutralization, (2) the pupillary reflex width is equal to the diameter of the smallest aperture of the observation system, (3) the relative speed of the pupillary reflex is equal to 1, that is, the speed of the reflex is that of the scanning speed, and (4) neutralization at infinity is independent of the observation distance. The lens used gives the "net" retinoscopy.

Care of cataracts.

Medical management may be beneficial for certain types of cataracts, depending on the visual needs of the patient and concomitant ocular or systemic conditions. Surgical intervention and postoperative visual rehabilitation with the use of glasses or contact lenses has a high success rate, although the patient should be followed closely for complications that can occur months to years after surgery.

Intraocular lens implantation: residents vs. staff.

Our first 96 consecutive IOL implantations were reviewed. Results of resident cases (85% maintaining 20/40 or better acuity at an average follow-up of 16 months) were comparable to those of staff physicians at our institution as well as to those reported in the literature by experienced implant surgeons. Results of residents' initial cases improved with changes in surgical technique and increasing experience of the assisting staff. Training of residents in implantation with adequate assistance represents no increased risk to the patient, and is likely to decrease the risk to subsequent patients encountered in practice.

Artificial eyes and tear measurements.

Ninety-four consecutive persons with unilateral enucleations or eviscerations were tested by the Schirmer I and Schirmer II tests for tear production. The findings on the artificial eye were compared with those on the companion, living (control) eye. The collected data were subjected to statistical analysis. The control eyes were shown to respond in the normal manner, more tears without topical anesthetic than with it. The sockets of artificial eyes produced no more tears without anesthetic than with it. The control eyes produced a normal amount of reflex tears, whereas the sockets of many artificial eyes produced practically no reflex tears. Tear production in persons with no complaints was compared to those with noteworthy problems. Persons with problems had only half as much basic tear secretion as those without problems. Elimination of the stimulus to reflex tear production by removal of the cornea and by the presence of the prosthesis is suggested as the cause of dryness of the eye socket. The potential value of aqueous or oily artificial lubricants is mentioned.

Central retinal artery occlusion and retinal tolerance time.

Transient central retinal artery occlusion (CRAO) was produced in 63 eyes of rhesus monkeys by lateral orbitotomy and temporary clamping of the central retinal artery (CRA) for between 15 and 270 minutes. Thirty-three eyes were examined at regular intervals for 12 to 22 weeks. Color fundus photography, fluorescein fundus angiography, electroretinography (ERG) and visual evoked response (VER) were performed before and during clamping of the CRA as well as periodically after unclamping. All the eyes were examined by light and/or electron microscopy. This study revealed that the retina suffered irreparable damage after ischemia of 105 minutes, but recovered well after ischemia of 97 minutes. As a general rule, the monkey retina can tolerate up to 100 minutes of ischemia but not more.

A new test of visual acuity using a holographic phase grating and a laser.

A new visual acuity testing device is able to determine a specific visual acuity of the retina even in the presence of opacities of the ocular media, such as a cataract. This is achieved by forming two spatially coherent, quasimonochromatic point sources near the nodal point of the eye. The two spherical waves that emanate from the point sources interact to produce a pattern of stripes on the retina. The intensity of the pattern is easily varied. More importantly, the pattern can be projected over different-sized retinal areas corresponding to visual fields of 0.5 to 15 degrees in diameter. The device may be useful for vision research and preoperative assessments of visual potential.

[Electroophthalmological characteristics in ischemic retinopathy (author's transl)]. / Elektroophthalmologische Charakteristika der ischämischen Retinopathie.

In the ERG the b-wave and the oscillatory potentials are reduced or nonrecordable in ischemic retinopathy. The photopic b-wave appeared to be more sensitive than the scotopic b-wave. In the EOG the slow oscillation is reduced. These clinical observations are in accordance with the results of experimental studies in rhesus monkeys.

Hereditary retinoschisis linkage studies in a family and considerations in genetic counselling.

We report a family with X-linked juvenile retinoschisis. In addition to the three males with severe visual impairment, six other males in this family were found to have hitherto undiagnosed disease. The findings in these mildly affected males are described in detail. The wide range of clinical manifestations found among the affected relatives initially hampered recognition of the correct diagnosis. Once the correct diagnosis was made, proper genetic counselling could be given. The data are compatible with loose linkage between the loci for juvenile retinoschisis and the red cell antigen marker Xga.