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Biomedical subjects

R S Ruiz

Publications and source records attributed to R S Ruiz.

At least 37 records · Page 2Linked to original sources
PubMed1989

Effects of carbachol and acetylcholine on intraocular pressure after cataract extraction.

We compared the effect of carbachol and acetylcholine on intraocular pressure 24 hours after extracapsular cataract extraction. All agents were administered intracamerally at the time of surgery. Sixty patients scheduled for routine extracapsular cataract extraction and intraocular lens implantation were randomly assigned into one of three treatment groups: (1) carbachol, (2) acetylcholine, or (3) 0.5% balanced salt solution (placebo). Baseline intraocular pressures were determined the day before surgery, and postoperative pressures were measured approximately 24 hours after surgery. The group intraocular pressures averaged over preoperative and postoperative values were 21.06 mm Hg in the acetylcholine group, 19.36 mm Hg in the control group, and 17.30 mm Hg in the carbachol group. The average difference between preoperative and postoperative intraocular pressure measurements for the three groups were 7.33 mm Hg for the acetylcholine group, 8.73 mm Hg for the control group, and 2.20 mm Hg for the carbachol group. Only carbachol was significantly different from placebo on statistical subsequent testing. Carbachol is suggested as the agent of choice both for achieving intrasurgical miosis and prophylaxis of increasing intraocular pressure after cataract surgery.

Acetylcholine↗
PubMed1988

A three-part system for refining intraocular lens power calculations.

A three-part system that determines the correct power for an intraocular lens (IOL) to achieve a desired postoperative refraction is presented. The three components are (1) data screening criteria to identify improbable axial length and keratometry measurements, (2) a new IOL calculation formula that exceeds the current accuracy of other formulas for short, medium, and long eyes, and (3) a personalized "surgeon factor" that adjusts for any consistent bias in the surgeon's results, from any source, based on a reverse solution of the new formula; the reverse solution uses the postoperative stabilized refraction, the dioptric power of the implanted IOL, and the preoperative corneal and axial length measurements to calculate the personalized surgeon factor. The improved accuracy of the new formula was proven by performing IOL power calculations on 2,000 eyes from 12 surgeons and comparing the results to seven other currently used formulas.

Evaluation Studies as Topic↗
PubMed1987

Management of increased intraocular pressure after cataract extraction.

We measured the change in intraocular pressure prospectively after extracapsular cataract extraction in 80 eyes after treatment with either pilocarpine gel, pilocarpine 4% solution, timolol 0.5% solution, or placebo. Intraocular pressure, pupil size, and anterior chamber cellular reaction were measured in a masked fashion on the first day after surgery. A significant increase in intraocular pressure was found in all groups postoperatively when compared with baseline values (P less than .001). Eyes treated with pilocarpine gel had an average intraocular pressure increase of 4.2 +/- 2.1 mm Hg (mean +/- 1 S.E.), eyes treated with pilocarpine 4% eyedrops had an average increase of 9.8 +/- 2.8 mm Hg, and eyes treated with timolol demonstrated an intraocular pressure increase of 8.25 +/- 3.19. The intraocular pressure in untreated eyes (controls) increased by an average of 12.9 +/- 2.7 mm Hg. Only the difference in intraocular pressure change between the eyes treated with pilocarpine gel and control eyes was statistically significant (P = .025). Postsurgical intraocular pressure exceeding 25 mm Hg was observed in three of 20 pilocarpine gel treated eyes (15%) and 11 of 20 control eyes (55%). Pilocarpine treatment was not associated with noticeable changes in intraocular inflammatory response, nor were significant ocular or systemic adverse reactions observed. A single administration of pilocarpine gel is effective in reducing increased intraocular pressure for the first 24 hours after extracapsular cataract extraction.

Cataract Extraction↗
PubMed1987

Brightness acuity test and outdoor visual acuity in cataract patients.

The disparity between functional outdoor vision and the acuity measured in the standard refracting lane is well known among clinicians. A simple device, the brightness acuity tester (B.A.T.), was developed to predict a patient's functional outdoor acuity. The B.A.T. has an illuminated hemispheric bowl, 60 mm in diameter, with a 12-mm aperture. Fourteen normals and 50 patients with cataracts were tested using the B.A.T. and then tested outside in bright sunlight. The B.A.T. correlated extremely well (r = +0.84, P less than .0001) with the acuities measured outside. There was no decrease in visual acuity in the 14 normal patients, but there was a one to ten line decrease in vision among the cataract patients. Upon retesting, the B.A.T. scores did not vary, while outside testing scores did change due to variable outdoor ambient light levels on sunny days. The B.A.T. is a simple, repeatable, useful test for predicting functional outdoor acuity.

Cataract↗
PubMed1986

Improving the predictability of intraocular lens power calculations.

We reviewed the intraocular lens power calculations on 512 posterior chamber lens implantations and determined four ways to reduce the estimated 5% incidence of large postoperative refractive "surprises" (greater than 2 diopters [D]): First, preoperatively identify those patients who have greater than a 1-D difference between the theoretical and linear regression formulas. Second, repeat axial length and corneal power measurements in these patients to eliminate random error. Third, develop an individualized theoretical formula that accounts for constant bias. Fourth, encourage manufacturers to improve instrumentation for measuring corneal power and axial length. We also examined the disparity between the linear regression formula and the curvilinear theoretical formula.

Anterior Chamber↗
PubMed1985

Pterygia as cause of post-cataract with-the-rule astigmatism.

Pterygia often induce with-the-rule astigmatism as they invade the cornea. Significant amounts of astigmatism occur long before a pterygium encroaches on the visual axis. We present an example in which a 3.3-mm pterygium resulted in 9 diopters (D) of with-the-rule astigmatism. Six weeks after the pterygium removal, the patient's cornea became spherical, but by three months the pterygium had recurred 2.2 mm onto the cornea and induced 4 D of with-the-rule astigmatism. Since the second removal and the application of beta irradiation, there has been no recurrence. The final correction was -1.00 + 1.00 X 127 degrees with a visual acuity of 20/20 +3. Characteristic keratoscopic photographs are shown and contrasted with surgically induced with-the-rule astigmatism.

Astigmatism↗
PubMed1983

Ophthalmology (eye physician and surgeon) manpower studies for the United States. Part IV: Ophthalmology manpower distribution 1983.

Physician distribution continues to be important in health manpower planning. In 1980 the GMENAC Committee reported uneven geographic distribution of physicians and uneven rates of use of health services in the United States. This study uses zip code sectional areas as the geographical units to describe the geographic distribution of ophthalmologists. Ophthalmologists to population ratio was calculated for each of 532 zip code sectional areas in the US. Results indicate considerable variation in availability of ophthalmologic services. However, this variation is not necessarily indicative of a serious maldistribution problem since there are regional differences in need and supply. This study found that less than 1% of the population did not have convenient access to an ophthalmologist. Resulting data should be helpful to both ophthalmologists considering relocating and residents seeking practice opportunities. Ratios should be used in conjunction with other demographic information available for the sectional areas.

Humans↗
PubMed1980

Intraocular pressure during enflurane and neurolept anesthesia in adult patients undergoing ophthalmic surgery.

The effects of neurolept and enflurane anesthesia on intraocular pressure (IOP) were studied in 20 patients undergoing elective ophthalmic surgery. Ten received neurolept and ten enflurane anesthesia. Continuous EEG tracings recorded the level of anesthesia. IOP was measured before and at intervals during anesthesia at varying concentrations of enflurane and incremental doses of fentanyl. During level I neurolept anesthesia IOP increased from control values of 18.10 +/- 0.93 mm Hg (mean +/- SEM) to 19.50 +/- 1.65 mm Hg, but decreased to 14.55 +/- 0.84 mm Hg during level II and to 12.29 +/- 1.13 mm Hg during level III anesthesia. During enflurane anesthesia IOP decreased from control values of 19.00 +/- 1.44 mm Hg (mean +/- SEM) to 14.50 +/- 1.60 mm Hg during level, I, 14.10 +/- 1.04 mm Hg during level II, and 11.60 +/- 1.46 mm Hg during level III anesthesia. The increase in IOP during neurolept level I anesthesia was not statistically significant but the decreases in IOP from control values during levels II and III anesthesia were statistically significant. Decreases in IOP from control values were statistically significant at all levels of enflurance anesthesia. There was, however, no statistical significance between the differences in IOP values during levels II and III neurolept anesthesia, nor between levels I, II, and III enflurane anesthesia. The differences in the mean IOP values between neurolept and enflurane anesthesia were statistically significant only during EEG level I anesthesia.

Adult↗
PubMed1979

Comparative evaluation of current ophthalmodynamometers.

Seventy-five patients under 40 years of age with no history of ocular, cardiovascular, or cerebrovascular disease were examined with four commonly used ophthalmodynamometers. There was a significant difference in the absolute values measured with each instrument and the ophthalmic to brachial artery pressure ratio. The standard deviations were comparable between 8.1 and 10.2%. The absolute value of the average percent difference between the right and the left eye ranged from 3.6% with the Galin unit to 6.7% with the Sisler unit. Limits of +/- 15% for ophthalmic artery to brachial artery pressure ratio and 10% for right to left pressure difference should be used for 95% confidence levels. There was a small but definite correlation between the ocular coefficient of rigidity and pressure differences between direct and indirect instruments.

Adolescent↗
PubMed1979

Acute retinal necrosis.

Three cases of acute retinal necrosis are presented. Acute retinal necrosis is an unusual syndrome which is the result of severe contusion to the globe. It is characterized by large irregular retinal holes with pieces of necrotic retina in the adjacent vitreous, retinal edema and hemorrhage surrounding the holes, underlying choroidal disruption, and vitreous hemorrhage. The incidence of acute retinal necrosis is difficult to determine but it does not appear to be common entity. Although acute retinal necrosis may be associated with a retinal detachment, other retinal breaks are usually responsible for the detachment. The necrosis results from the direct force of the injury striking the globe although a contrecoup mechanism may explain cases of nasal necrosis. Treatment is necessary for associated retinal detachments and acute lesions but may not be necessary if adequate fibrosis is present when the lesion is first seen.

Acute Disease↗
PubMed1978

Massive spontaneous subretinal hemorrhage.

We studied eight cases of massive, spontaneous subretinal hemorrhage which was characterized by the sudden appearance of one or more large, dark, elevated hematomas under the retina. The initial location of the hemorrhage may have been in the choroid or under the pigment epithelium, or both, but further extravasation of the blood anteriorly frequently resulted in hemorrhage under the neurosensory retina and in the vitreous. Although the lesion can initially be mistaken for a melanoma, the diagnosis is confirmed by the formation of a typical, elevated scar in the involved area. Frequent fundus examinations are essential, and ultrasound, radioactive phosphorus uptake testing, and bilateral patching are helpful in establishing the diagnosis. The hemorrhage is usually the result of a ruptured vessel from a subretinal neovascular network or arterioclerotic degeneration and may be precipitated by the use of anticoagulants.

Adult↗