John H. Carter

Dapiprazole clinical efficiency for counteracting tropicamide 1

We evaluated the clinical usefulness of dapiprazole in reversing the effects of tropicamide 1.0%. Our study was random, masked with placebo, and used one eye of each subject as a control. Thirty subjects were given dapiprazole as directed by the manufacturer 30 min after being dilated by one drop each of proparacaine 0.5%, tropicamide 1.0%, and then 5 min later another drop of tropicamide 1.0%. Pupil diameter, amplitude of accommodation, conjunctival injection, and intraocular pressure were evaluated. Each of these variables was measured: (1) before instillation of the diagnostic agents; (2) before the instillation of dapiprazole; and (3) at 30, 60, 120, and 180 min after the final instillation of dapiprazole. The average pupillary recovery time for dapiprazole-treated eyes was significantly less than for nontreated eyes. Accommodation also showed faster recovery. Comfortable reading ability returned after approximately 43 min with dapiprazole vs. 66 min without dapiprazole. All of our subjects exhibited conjunctival hyperemia after the administration of dapiprazole. This persisted throughout the 180 min observation period after its administration.

An over-refraction program for the TI 59 card-programmable calculator.

Over-refraction provides a powerful method for the refractive examination of the aphakic or highly ametropic patient. Nevertheless, in the past, practical difficulties that attend mathematical or graphical combination of over-refraction and original spherocylinders have tended to limit the clinical use of over-refraction methods. Programmable calculators, now available inexpensively, render over-refraction clinically practical. An over-refraction program for the Texas Instruments TI-59 Card-Programmable Calculator is presented. Program running time, exclusive of data entry and readout, is under 15 sec.

Analysis of a "G-day" program.

&NA; “G‐Day” programs frequently have been employed to detect previously undiagnosed cases of glaucoma. Often, such programs have used elevated intraocular pressure as their sole basis for referral. The results of one such voluntary program have provided data which suggest the following: (1) The incidence of previously‐undiagnosed glaucoma (for an overall sample of 2,244 persons) was probably about 1.3%; (2) Public participation appears to have been greatest among those approaching retirement age, being substantially less among both those of early middle age and those well past normal retirement age; (3) The percentage of referrals varied little from community to community; (4) The percentage of referrals varied only slightly from one general age level to another: (5) Among those referred for complete glaucoma workups, the frequency with which “clean bills of health” were obtained declined markedly with advancing age; and, (6) An unequivocal diagnosis of glaucoma was found to be less common among elderly screenees than among those of advanced middle age.

A system of retinoscopy for the aged eye.

A method of retinoscopy is described in which an optical arrangement magnifies the patients pupil and makes it easier to see the retinoscopic reflex. At the same time, the method permits retinoscopic observation by the emmetropic examiner without need for accommodation, a distinct advantage to the presbyopic examiner. The relationship between retinoscope position and dioptric power-error is linear, a feature that facilitates cylinder determination using a variable-distance technique.

Ophthalmometric prediction of correcting cylinder axis.

Abstract One clinical use of the ophthalmometer is to aid in the prediction of the correcting cylinder for the eye, thereby to provide a starting point for retinoscopic and/or subjective testing. When axis is known in advance with reasonable accuracy, correcting cylinder refinement is accomplished easily, but when the predicted axis is in substantial error, perhaps by as much as 90°, then a starting point has little value and refinement gives way to primary determination. For optical reasons, the accuracy of predicting the correcting cylinder axis increases with corneal toricity. Therefore, the clinical value of the ophthalmometer as a predictor of the correcting cylinder increases with escalating corneal toricity. The procedure followed in this paper has been first to assess, through Monte Carlo simulation, the accuracy of the prediction of correcting cylinder axis as a function of direction and amount of corneal astigmatism. I then considered the effects of potential errors in analysis that might result from uncertainty as to the actual values of certain parameters. Greatest uncertainty appears to attend variance of the axis of the residual astigmatism. It is suggested that the minimum amounts of astigmatism which provide reasonable assurance that the axis of the correcting cylinder will lie within ±10° of its ophthalmometrically predicted value at least 90% of the time are: (1) 2.25 D, for W‐T‐R astigmatism; (2) 1.50 D, for A‐T‐R astigmatism; and (3) 2.25 D, for oblique astigmatism.

Dapiprazole's effect upon accommodative recovery: is it due entirely to changes in depth of field?

We conducted a study to evaluate the ability of dapiprazole 0.5% ophthalmic solution to reverse accommodative loss brought about by mydriatic drugs having mild cycloplegic effects. To accomplish this, we analyzed data from several earlier randomized, masked clinical studies. Our composite data include over 90 subjects dilated with tropicamide. Tropicamide was used alone in 1% concentration, as well as in combination with phenylephrine, 2.5% and in the proprietary preparation, Paremyd (Allergan Pharmaceuticals). Accommodative amplitude and pupillary diameter were measured before instilling dilating drops and then again one-half hour later, immediately before instilling either dapiprazole or a placebo. Accommodative amplitude and pupil diameter measurements were then repeated four more times, on both the treatment and control eyes and at 30, 60,120, and 180 min after instillation of the last drop of dapiprazole or placebo. We found accelerated “accommodative” recovery with dapiprazole for each of the three tropicamide-containing drugs used in our study. This is not surprising because some recovery of accommodative amplitude after dapiprazoles administration is expected. This is because dapiprazole accelerates pupillary recovery and a narrowing of the pupil gives rise to an increase in ocular depth of field. Rate of accommodative recovery with dapiprazole was found not to be significantly different for all three tropicamide-containing preparations tested (p>0.05). Does dapiprazole produce improvement in amplitude of accommodation beyond that attributable to increased depth of field? To answer this question, we performed calculations to determine the amounts of amplitude presumably free from the effects of depth of field. We found differences in amplitude measured with and without dapiprazole, after each had been adjusted so as to exclude the effects of depth of field. “True” (adjusted) amplitudes with dapiprazole ascended more rapidly than amplitudes without dapiprazole. Differences ascended to just over a diopter by 60 min, falling below a diopter again between 120 and 180 min.

An evaluation of UV-fluorescent methods of campimetry.

ABSTRACT In recent years, there has been growing use of visual field test methods which utilize UV‐fluorescent stimuli. Such stimuli are typically irradiated by filter‐type fluorescent UV sources and they are usually viewed in otherwise near darkness. In spite of an apparently growing clinical acceptance of such field test techniques, there has in the past been little evidence to support their validity. Furthermore, practitioners who plot form fields using UV‐fluorescent test objects perhaps most often make the tacit assumption that the stimulus value of a blacklight‐irradiated, UV‐fluorescent target is the same as that of a diffusely‐reflecting white test object of the same size, illuminated and viewed under standard conditions. Results of the present investigation are consistent with the assumption that UV‐fluorescent methods of campimetry are fundamentally valid. That is to say, such methods appear to reflect the same variables as do the more conventional forms of campimetric investigation. On the other hand, subject‐to‐subject differences appear to be too great to permit the formulation of a meaningful table of UV‐fluorescent versus diffuse white test object equivalents for universal application.

On the brightness of the fluorescein glow.

ABSTRACT A study was undertaken to determine how the luminance of aqueous solutions of sodium fluorescein varies with concentration and with thickness. While over a wide range of concentrations luminance increases in approximate accord with the +0.9 power of concentration, the relationship between concentration and luminance appears to become inverse for low dilutions. Luminance seems to increase almost linearly with thickness, at least for thicknesses to five millimeters.