Biomedical subjects

M C Kraff

Publications and source records attributed to M C Kraff.

46 records · Page 3Linked to original sources

PubMed1980

Improvement of intraocular lens power calculation using empirical data.

A simple lens power calculation formula of the form: Predicted implant power = A + B X axial length + C X keratometry, can be produced with different constants (A, B, and C) for each type of lens implant and each manufacturer. We have determined the constants for iris-fixated, anterior chamber and posterior chamber lens implants, based on data from 923 cases. The results have been more accurate than those from presently available theoretical formulas, and the well-known phenomenon of predicting too much dioptric power in eyes with short axial lengths has been avoided. Only 1% of the cases had a predicted lens power more than 3 diopters in error.

Cornea↗

PubMed1980

Slit-lamp fluorophotometry in intraocular lens patients.

Two hundred and sixty-four patients who had unilateral implant surgery and normal contralateral unoperated eyes were studied by slit-lamp anterior segment fluorophotomety. Patients tested five weeks to six months after surgeryb averaged 22% more fluorescein in the operated than in the unoperated eye, while those tested after six months averaged only 12% more fluorescein. Patients receiving topical indomethacin demonstrated an 11% increase in fluorescein, while those taking a placebo averaged a 33% increase. Patients with cystoid macular edema averaged a 46% increase in fluorescein compared with a 17% increase in the other patients. Twenty-seven control patients with unilaterally aphakic eyes and normal contralateral unoperated eyes, tested on an average of two years after surgery, showed essentially no increase in fluorescein in the operated eye. Fluorophotometry may be a valuable clinical tool in testing the effect of drugs on the blood-aqueous barrier and to screen patients for cystoid macular edema.

Aqueous Humor↗

PubMed1980

Normal endothelial cell count range.

It was the purpose of this study to determine whether age could be used to predict central endothelial cell count in preoperative cataract patients aged 40 to 90. Three separate series of cell counts on a total of almost 3,000 eyes were performed and analyzed regarding age relationship. Although statistically endothelial cell count appears to decrease with age, the decrease is so small that a large range of cell counts was noted for each age. The results of this study indicate that age is not useful in estimating endothelial cell count in this population.

Adult↗

PubMed1979

300 primary anterior chamber lens implantations: gonioscopic findings and specular microscopy.

A total of 300 consecutive quadruped anterior chamber intraocular lenses were implanted. Gonioscopy was performed in all cases and prospective specular microscopy was performed in the last 97 cases. Iris tucking of at least one lens foot was noted in 28% of the cases. Tucking occurred less often (20% of the cases) when the lens length was 13 mm, increasing with lens lengths longer and shorter than 13 mm. Slight lens rotation was noted in 8% of the cases. Blood vessels (rarely appearing to be neovascular) were noted around an implant foot or in the anterior chamber angle near a lens foot in 30% of the cases. A statistically significant difference in endothelial cell loss was noted between the Choyce lens (18.6%) and the Tennant lens (12.4%).

Anterior Chamber↗

PubMed1979

The Medallion suture lens: management of complications.

In a study of 613 Medallion suture implant patients, 87% of the 613 and 96% of those under 70 years of age had a postoperative visual acuity of 20/40 or better. The most common operative complication was corneal endothelial trauma, which was graded and correlated with endothelial microscopy; however, only 0.5% of cases had permanent corneal opacification. Cystoid macular edema occurred in 32 cases (5.2%), and 56% (18) of these patients regained 20/40 vision or better. Implant loop subluxation occurred in 19 cases (3.1%), but this incidence should decrease by increasing implant loop tip-to-tip distance. The data presented put in perspective the relative importance of the various complications encountered, with primary emphasis on the management of these complications.

Astigmatism↗

PubMed1979

Total cataract extraction through a 3-mm incision: a report of 650 cases.

We treated 650 consecutive cases of phacoemulsification with total capsulectomy. More than 91% of cases had best corrected visual acuities of 20/40 or better. In those with vision of 20/100 or less (3.5%) no cause for decreased acuity could be related to the surgery; 94% of cases had less than 1.5 diopters of residual astigmatism. Vitreous loss, occurring in 2.9% of cases, could be related to initial inexperience and errors in technique rather than patient age. Postoperative complications included transient striate keratitis (2.3%), persistent corneal edema (one case), cystoid macular edema (2.8%), and aphakic retinal detachments (2.6%). There were no hyphemas, flat or shallow anterior chambers, or filtering blebs postoperatively. We believe that this technique of total cataract extraction through a 3-mm incision yields the same results as an intracapsular extraction, but with less complications, and all the benefits of a small limbal incision.

Adult↗

PubMed1978

Biometric analysis of intraocular lens power required to produce emmetropia: results of 450 implants.

We analyzed 450 consecutive cases of intraocular lens implantation (omitting only two inadvertent implantations in patients with high myopia) to determine the dioptric lens power in each case required to produce emmetropia. The mean was 18.3 D with a standard deviation of 2.6 D. The data did not conform to a normal or Gaussian distribution because of an abnormally high number of cases that required greater than 25 D to achieve emmetropia and clustering between 17 to 19 D. The deviation from a normal distribution may be explained by our considering patients with high hyperopia and high myopia (which are for the most part excluded from intraocular lens data) to be separate populations. The data are valuable to the intraocular lens surgeons, in that they demonstrate the range and frequency of intraocular lens powers needed to achieve emmetropia in a large population sample.

Aphakia↗

PubMed1978

Endothelial cell loss and trauma during intraocular lens implantation: a specular microscopic study.

We analyzed the results of a retrospective specular microscopic study of 80 cases with unilateral medallion suture implants and contralateral unoperated eyes. In all cases a clinical estimation of operative endothelial trauma (ET), graded from 0 to 3+, was made at the time of surgery. The mean decrease in endothelial cell density (compared to the unoperated eye) for those 33 patients with ET 0 was 19%. There was a direct correlation between ET and decrease in endothelial cell density up to a mean of 59% for those 18 patients graded ET 2.5 to 3.0. The role of sample bias and small case sampling is significant in explaining the large discrepancy in endothelial cell loss after intraocular lens implantation reported in the literature.

Cell Count↗

PubMed1978

Determination of intraocular lens power: a comparison with and without ultrasound.

Two consecutive and sequential series of 100 pseudophakic patients were compared. In the first series intraocular lens power was determined by clinical means. In the second series axial length, using an easily operated commercially available A-scan unit, keratometry, and estimation of anterior chamber depth data were entered into an electronic calculator programmed to determine intraocular lens power. In the first series 47% of patients had a residual refractive error of 1 diopter or less, whereas 72% were within this range in the second series. With clinical lens power determination, there were three cases of residual deviation from emmetropia of more than 4 diopters; there was none greater than 3 diopters in the group using the A-scan. Lens power determination is more accurate using ultrasonography and the presently available instrumentation can be incorporated easily into a busy private practice.

Humans↗

PubMed1977

Experience with the large circular loop medallion lens and a critical comparison with the suture medallion lens: a report of 300 cases.

An iris-supported intraocular lens must have stable fixation to minimize postoperative complications. A series of 46 large circular loop Medallion lenses were implanted after intracapsular cataract extraction and compared with a series of 254 suture Medallion lenses. An unexpectedly high incidence of lens dislocation and iris damage occurred with the large circular loop Medallion lens implants. Based on our results, we believe that the large circular loop Medallion lens should not be used for implantation after intracapsular cataract extraction at this time. The suture Medallion lens provides a standard to which other pseudophakai may be compared.

Aged↗