Central corneal thickness (CCT) of normal and oedematous corneae was measured in a study comparing a modified Haag-Streit optical pachometer and an ultrasonic pachometer (Teknar Ophthasonic, preset velocity 1630 m/s). Sixty-eight patients were examined before and after cataract extraction with implantation of an anterior chamber lens. Mean values of CCT before operation were 531 +/- 4.9 (SEM) micron by optical pachometry and 524 +/- 4.7 microns when measured by ultrasound (not significantly different). On the first post-operative day the values were 618 +/- 8.4 and 602 +/- 7.6 microns for optical and ultrasonic measurements, respectively (significantly different, 2P less than 0.001). Correlation analysis showed a high dependence between the methods with coefficients of correlation being 0.955 before and 0.958 after the operation. Linear regression analysis revealed small, but significant differences between the techniques. The difference between the two methods increased with increasing corneal hydration, whereas it could not be ascribed to sex, age, or intraocular pressure. It is concluded that for clinical purposes optical and ultrasonic pachometry techniques are comparable.
Morphological changes and lens position were examined in 51 patients 25 to 38 (mean 30) months after intracapsular cataract extraction (ICCE) with implantation of the semiflexible, 3M, style 70, anterior chamber lens. Morphological changes presumably associated with the ICCE proper were: iris transillumination defects (68.6%), rupture of anterior hyaloid membrane (20%), detachment of posterior vitreous (42.9%) and anterior synecchiae (13.7%). The implant-related morphological changes were caused by iris tucking (19.6%), small, mobile lenses causing endothelial disturbance (9.8%), iris-haptic adhesions and progressive ovalling of pupillary form. The present morphological changes were compared with a previously published examination of the same patients performed 4 months after surgery: 9 eyes without tissue changes around the lens feet at the previous follow-up now had iris-haptic adhesions involving from 1 to 4 lens feet. In 8 eyes the iris-haptic adhesions had progressed. Compared with the previous examination the fraction of eyes with tissue changes at the lens feet had risen from 47.1 to 64.7%, while the number of eyes with oval pupils had increased from 54.9 to 80.4%. Contact between lens haptic and iris root seems to constitute a constant stimulus for structural changes of the iris.
In a prospective study of 89 patients the postoperative corneal edema and endothelial cell count was studied after cataract extraction. A double blind investigation was performed as the patients during the first 6 postoperative days were treated with three different types of eye-drops: Maxidex, Pred-Forte 1% or placebo, all containing Benzalkonium Chloride 0.004%. The content of steroid in Maxidex and Pred-Forte was equivalent. We found no significant difference in estimates of endothelial cells in the three groups postoperatively. Corneal edema was less in the two groups treated with steroid. There was no significant difference between the two postoperative groups (p > 0.05) treated with Maxidex and Pred-Forte. The group treated with Pred-Forte showed significantly less postoperative corneal edema, calculated as the graphical area represented by the increase of central corneal thickness (CCT) after operation.
Sixty-four patients were consecutively operated for senile cataract with implantation of the semiflexible McGhan/3M, style 70, anterior chamber lens. Intraocular pressure (IOP) was measured one day prior to the operation, 6 days and 3-8 months (mean 4 months) after the operation, and gonioscopy was performed one day prior to and 4 months after the operation. A significant fall in IOP was found in the operated eye 6 days after surgery. No significant change in IOP was found 4 months after surgery, neither in the operated eye nor in the non-operated fellow eye. Iris tucking seemed to have no influence on the post-operative tension, while a significant rise in IOP was found in 13 eyes with adhesions between the iris and lens haptics as the only abnormal gonioscopic finding.
The influence of systemic antifibrinolytic and antiprostaglandin medication on post-operative central corneal thickness was studied. Thirty patients underwent uncomplicated intracapsular cataract extraction with implantation of anterior chamber lens. The patients received either tranexamic acid, naproxen or both. The post-operative oedema did not differ significantly between the three groups studied. Models for studying changes in central corneal thickness are discussed. A review of the influence of drugs on corneal thickness is presented.
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