Influence of menstruation on corneal sensitivity.

Abstract

Intraocular pressure has been shown by Dalton (i 967) to increase during the paramenstruum of women with closed-angle glaucoma. It is also known that there is a reduced corneal sensitivity with an increase in intraocular pressure as in glaucoma (Boberg-Ans, I955). However, it is not known if corneal sensitivity of the healthy eye varies during the menstrual cycle and this study reports on the variations of the corneal touch threshold ofyoung women during the menstrual cycle. We found a significant decrease in corneal sensitivity corresponding with the paramenstruum which was not found either in women taking oral contraceptives, or in men, who served as control groups. Material and methodsThe subjects were divided into three groups. (I) Nine females, two of whom were tested daily and the remaining seven were asked to report I4 days and 24 hours before the onset of menstruation and again I4 days later.(2) Five females taking oral contraceptives tested at the same i4-day intervals, except for one who was measured daily.(3) A control group of eight males, one of whom reported daily and the others at x4-day intervals.All subjects were free of ocular pathology and between 2 I and 31 years of age, and all were tested on the right eye only.The Cochet-Bonnet Aesthesiometer (Cochet and Bonnet, i960), based on the instrument devised by Boberg-Ans (I955), was used to stimulate the cornea. Two models of the instrument, with nylon monofilaments of o I 2 and o-o8 mm. diameter, were used to produce pressures of from I I to 200 mg./ OOI13 mm.2 and from 2 to 90 mg./0o005 mm.2 respectively. The aesthesiometer was mounted in a holder, allowing movement in x, y, and z axes, so that reliability in stimulation of a corneal point, steady speed of application (Boberg-Ans, I956), and a perpendicular corneal contact was achieved. A corneal point near the limbus in the 6 o'clock position was stimulated and the slightest bend of the nylon wire visible through a x 4.3 magnifier was defined as corneal contact. All measurements were taken when the humidity was between I 5 and 35 per cent. because the nylon monofilament is affected by humidity (Millodot and Larson, i967). Subjects were tested at the same time of day to avoid confusion with the diurnal variation in corneal sensitivity (Millodot, 1972).The touch threshold was determined subjectively (Millodot, I973). The measurements began with stimulation of the cornea at the lowest pressure and continued in an ascending fashion. At each determined length of the nylon monofilament four to six contacts were made, with at least one blank to test subject reliability. The subject indicated when he felt the probe by pressing a bell. From these readings the touch threshold was defined as the length of the monofilament for which the subject responded for 50 per cent. of the number of stimulations. This length was converted into pressure using the calibration curve of the instrument relating length and pressure previously established (Millodot, I969).

Identification of androgen, estrogen and progesterone receptor mRNAs in the eye

“…Similarly, it has yet to be definitively established whether these sex steroid receptors play a significant role in the: [a] diverse ocular changes that occur during the menstrual cycle, menopause and pregnancy (Guttridge 1994;Imafidon & Imafidon 1992;Imafidon et al 1993;Millodot & Lamont 1974;Qureshi 1997;Ruben 1966;Serrander & Peek 1993); [b] gender-related differences in meibomian gland lipid release, corneal wetting time, corneal epithelial mitotic rate, conjunctival goblet cell density, lens epithelial cell number, intraocular pressure and visual acuity (Chew et al 1993;GuggenmoosHolzmann et al 1989;Klein et al 1991;Moore et al 1987;Norn 1969;Qureshi 1997;Tsai et al 1985); or [c] gender-associated variations in the incidence of dry eye syndromes, glaucoma, cataracts, agerelated maculopathy, macular holes, macular degeneration, retinal detachment diabetic retinopathy and visual impairment (Caffery et al 1998;Guttridge 1994;Guyer and Gragoudas 1994;Hiller et al 1986;Kahn et al 1977;Klein et al 1984Klein et al , 1992Klein 1994;Richardson et al 1995;Sullivan 1997).…”

Keratoplasty sensitivity.

“…In normal cornea the central zone is about 2 to 3 times as sensitive as the periphery (Millodot and Larsen, 1969). But age, individual apprehension, and even time of the day or month in women will cause some significant change in the degree of sensation (Millodot and Lamont, 1974).…”

The influence of pregnancy on the sensitivity of the cornea.

“…Corneal sensitivity has been shown by Millodot and Lamont (1974) to decrease during the premenstrual phase of the woman's menstrual cycle. Many of the changes occurring during the premenstrual phase are similar to those of pregnancy (Best and Taylor, 1945).…”