Only few studies are available on changes in corneal sensitivity during pregnancy, and most of the earlier work was done with instruments which gave only a rough approximation of the threshold of corneal sensitivity to touch. The new esthesiometer developed by Draeger permits, for the first time, an exact and reproducible determination of the threshold of corneal sensitivity to touch. We studied corneal sensitivity in 86 pregnant women between the 13th and 40th week of gestation. The thresholds were significantly higher in the study group as compared to a control group of non-pregnant women. The decrease in corneal sensitivity was not related to duration of gestation, weight gain during pregnancy or mean arterial pressure at the time of examination. Possible mechanisms responsible for changes in corneal sensitivity in pregnancy are discussed.

SUMMARY Corneal sensitivity was determined in 5 women with regular menstrual cycles by means of a new aesthesiometer developed by Drager. Throughout one menstrual cycle we measured corneal touch thresholds (CiT) daily and did serial determinations of urinary luteinising hormone and pregnanediol levels. CTT rose in 4 women with proved ovulation in the days before or on the day of ovulation, while corneal sensitivity remained unchanged in one anovulatory subject. We observed no changes in CTT prior to menstruation. The decrease in corneal sensitivity might be related to the preovulatory oestrogen peak.A reduction in corneal sensitivity in the female occurs not only after operations on the eye, in various metabolic diseases, and after long-term use of contact lenses, but also in relation to physiological changes of the organism, for example during pregnancy.' Therefore one might assume that corneal sensitivity of the healthy eye also varies during the menstrual cycle. Millodot and Lamont described a significant reduction in corneal sensitivity in the days prior to the onset of menstruation.2 These authors measured corneal sensitivity in 2 women daily and in 7 women at intervals of 2 weeks during the menstrual cycle by means of a Cochet-Bonnet aesthesiometer.With the introduction of the electromagnetic aesthesiometer of Drager a quantitative and reproducible method for the determination of corneal touch threshold (CiTT) became available.34 The purpose of the present study was to assess corneal touch thresholds with this new aesthesiometer during the menstrual cycle and to relate possible changes in corneal sensitivity to serial measurements of luteinising hormone and pregnanediol. Patients and methodsFive healthy women between the ages of 21 and 35 years (mean age 26-8 years) with no eye disease and regular menstrual cycles volunteered for this study. Corneal touch threshold was assessed daily during one menstrual cycle. All examinations were performed by the same author in a separate room between 8 and 10 a.m.5Correspondence to Dr Brigitte Riss. First Department of Ophthalmology. Spitalgasse 2. A-1090 Vienna. Austria. 123The electromagnetic aesthesiometer of Drager was used in order to obtain reproducible values for corneal touch threshold.34 The instrument consists of a metal tactile probe with a diameter of 0-5 mm. In order to avoid a ballistic effect the probe is approximated with nonlinear velocity. The probe touches the cornea at a right-angle under direct vision of the examiner.

5-Fluorouracil was used to inhibit experimental intraocular proliferation in rabbit eyes, produced by homologe fibroblast implantation. Two different concentrations were used, 1 and 5 mg in a single intravitreal injection. The eyes were followed up over 4 weeks. Proliferation and resulting traction detachment was reduced from 75% to 30% in the 1-mg 5-fluouracil group. In addition, we observed retinal and vascular changes in a considerable number of eyes treated with 1 mg and much more pronounced alterations in most of the eyes treated with 5 mg fluouracil.

5-Fluouracil, administered at concentrations of 1 and 5 mg to inhibit experimental intraocular proliferation produced by intravitreously implanted fibroblasts in rabbits, produced tissue alterations revealed by TEM. The degranulation and migration of pigment epithelial cells, the incipient degradation of axons and myelin sheets, the migration of glial cells and the prominent edema of the inner layers indicated a non-negligible damage to the retina, suggesting to abstain from its use in human eyes and to search for less neurotoxic drugs, possessing the same inhibitory effect on intraocular proliferation.

The corneal touch threshold (CTT) was determined in 35 eyes before and after retinal reattachment operations. In some cases the CTT of the unaffected eye was taken for comparison. The new aesthesiometer developed by Draeger in 1977 was used and measured CTT in the center of the cornea and in the 12, 3, 6, and 9 o'clock position 1 mm from the limbus. Thirty eyes (86%) showed a rise in CTT after retinal reattachment operations, irrespective of the method of anaesthesia used, and the decrease in corneal sensitivity was observed for up to a period of 5 years postoperatively. Loss of corneal sensitivity was more marked in operations with diathermy and scleral pocketing than in cases with cryopexy and plombage operations. Extremely high CTT values were observed in eyes that underwent encircling procedures, cryopexy, vitrectomy, and gas injection. There was a significantly higher decrease in corneal sensitivity after encircling procedures than after plombage operations.