Readings with the Goldmann applanation tonometer were made at various intraocular hydrostatic pressures and compared with central corneal thickness and radius in rabbit and in man. Linear correlations were established between hydrostatic pressure and applanation readings, with correlation coefficients close to 1.0. In rabbits the tonometer readings were generally too low. In human eyes with a normal corneal thickness tonometer readings and hydrostatic pressure coincided, with thick corneas the readings were too high, with thin corneas too low. The correlation between corneal thickness and the error of applanation tonometry (LIP) was statistically highly significant (P < 0.001). No statistical correlation could be established between corneal radius and AP. Multiple regression, taking thickness as well as corneal radius into consideration, revealed only slightly higher correlation coefficients. It is concluded that the central corneal thickness is a parameter which should be taken into consideration when evaluating applanation tonometer readings. A Table is presented showing the correction to be added to the applanation reading at differing corneal thickness. A clinical study of the normal human central corneal thickness. Kruse Hansen, F. PC Ehlers, N. (1971) Elevated tonometer readings caused by a thick Mishima, S. & Hedbys, B. 0. (1968). Measurement of corneal thickness with the Haag-Acta ophthal. (Kbh.) 49, 82-89. cornea. Acta ophthal. (Kbh.) 49, 775-778. Streit pachometer. Arch. Ophthal. (Chicago) 80, 710-7 13.

. Purpose:  To estimate the prevalence and incidence of hospitalized keratoconus (KC) in Denmark. Methods:  Data extracts from the National Patient Registry under the National Board of Health (which covers the entire Danish population) were analysed. Results:  The prevalence of KC was estimated at 86 patients per 100 000 residents and the incidence at 1.3 per 100 000 per year. Conclusion:  KC is rather widespread in Denmark, with more than 4600 affected individuals.

Our data, thus, indicate that hypoxic exposure has the capacity to sustain long-term self-renewal of hESCs and that this effect is mediated through activation of Notch.

ABSTRACT.Purpose: To compare the outcome of Descemet's stripping endothelial keratoplasty (DSAEK) to that of penetrating keratoplasty (PK) in patients with Fuchs' endothelial dystrophy. Methods: The first 20 patients who underwent DSAEK at the Department of Ophthalmology, Aarhus University Hospital were compared to 20 patients treated with classic PK. Best-corrected visual acuity, subjective spectacle refraction and corneal thickness were registered before surgery and 1, 3, 6 and 12 months after DSAEK surgery; they were also measured before surgery and 12 months and 2-3 years after PK. Endothelial cell density was measured 12 months after surgery in both groups. Results: Two primary graft failures were observed in the DSAEK group; no failures were seen in the PK group. Best spectacle-corrected visual acuity (BSCVA) at 12 months after surgery was significantly better in the DSAEK group (0.56 ± 0.04) than in the PK group (0.33 ± 0.06). At this time, 70% of the DSAEK-treated eyes but only 25% of PK-treated eyes had obtained a BSCVA of 0.5 or better. Two to three years after surgery, BSCVA was 0.5 or better in 55% of PK-treated eyes. Refractive ametropia and astigmatism were significantly smaller in DSAEK-treated eyes than in PK-treated eyes, even after suture removal and arcuate keratotomy. Endothelial cell density (cells ⁄ mm 2 ) after 1 year was lower in DSAEK-treated (1.338 ± 113) than in PK-treated eyes (1.610 ± 124), but the difference was not statistically significant. Conclusion: DSAEK seems to be superior to PK in treating Fuchs' endothelial keratoplasty, although primary graft failure may be more common. Visual recovery is faster, and major ametropia and astigmatism is not induced. Longterm follow-up studies are essential to assess whether this conclusion also holds true more than 1 year after surgery.

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