The role of central corneal thickness in the diagnosis of glaucoma.
OBJECTIVE
To determine the effect of central corneal thickness (CCT) on applanation tonometry and any resultant misclassification of normals as ocular hypertension.


METHODS
The central corneal thickness was measured using the ultrasound pachometer in 50 normals, 25 glaucoma and 23 ocular hypertensive patients. The student's "t" test was used to determine any significant difference in CCT between the three groups.


RESULTS
There was a statistically significant difference in the mean CCT of the ocular hypertensives (0.574 +/- 0.033 mm) as compared to the glaucomas (0.534 +/- 0.030 mm) and normals (0.537 +/- 0.034 mm). Applying the described correction factor for corneal thickness, 39% of eyes with ocular hypertension were found to have a corrected IOP of 21 mmHg or less.


CONCLUSIONS
Increased corneal thickness in ocular hypertension may lead to an overestimation of IOP in 39% of cases. Measurement of central corneal thickness is advisable when the clinical findings do not correlate with the applanation IOP.
Thomas
R
R
Schell Eye Hospital, Department of Ophthalmology, Vellore, India. ravi@schell.cmc.ernet.in
Korah
S
S
Muliyil
J
J
D000328:Adult; D003315:Cornea / Q000473:pathology*; D003937:Diagnosis, Differential; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis*; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis; D011446:Prospective Studies; D014065:Tonometry, Ocular