Central corneal thickness and intraocular pressure in Kenya
Abstract
Title: Central Corneal thickness and intraocular pressures in Kenya.
Objective: The main objective of this study was to establish the central corneal
thickness in selected Kenyan communities.
Rationale: Studies done in Caucasians and African Americans suggest that Africans
have thinner central corneas and this leads to an underestimation of
intraocular pressures. Hence patients may end up not receiving appropriate
, treatment with subsequent glaucomatous damage and loss of vision that might
have been avoidable.
Statement of the Problem:
Intraocular pressure is an essential eiement in the management of glaucoma.
CCT has been identified as a potential source of error in the measurement of
lOP (1-2).
Estimates of intraocular pressure by applanation tonometry are influenced by
CCT. We assume and apply a specific value for CCT in applanation
tonometry estimates as the Goldmann equation is based on theoretical
calculations accurate at CCT of 520 micrometers. However, there lS
compelling evidence that CCT varies between individuals, with ethnicity.
Failure to adjust lOP estimates of variation In CCT influences clinical
decision-making. The underestimation of lOP due to thin cornea may delay
the diagnosis and treatment of glaucoma. There is also the risk of pseudoocular
hypertensive patients being subjected to inappropriate treatment in
cases 0 f thicker CCT (3)
The measurement of CCT may playa role in the clinical evaluation of lOP
with a baseline CCT to be obtained for patients with suspected glaucoma. The
American Academy of Ophthalmology (J) reports that this recommendation
presents Ophthalmologists with a dilemma: there is no single formula to
recalculate lOP as the relationship between CCT and lOP is not linear and
there is no accepted universal algorithm (2, 25).
Methodology: A total of261 eyes of 132 patients were examined. Three patients had only
one eye included in the study as their contralateral eyes had corneal
pathologies.
Three hospitals with eye units were selected representing three major ethnic
groups in Kenya: that is Sabatia Hospital, Litein AlC Mission Hospital and
Isiolo District Hospital - had their Central Corneal Thickness, Goldmann
..
Applanation Tonometry and Schioetz Indentation Tonometry readings where
applicable.
Results: A total of 261 eyes of 132 patients were analyzed for CCT, GAT and SIT.
There were 71 males (54%) and 61 female (46%) respectively.
Bantus contributed ,143, Nilotes 90 and Cushites 28. Using Levene's Test for
Equality of Variance. P was 0.013 at a mean difference of± 15.54. This is
statistically insignificant and variation in sample numbers did not affect the
fmal results ofCCT, GAT and SIT.
The mean CCT was 521.43 micrometers, with a GAT mean of 15.04mmHg
and a SIT mean of 14.393mmHg. This mean CCT of 521.43 micrometers is
lower than that established by other studies of 555-573 micrometers. (3,9,20,35,
38,4J,42,44). The mean CCT for the three ethnic groups were 521.76, 524.72 and
509.18 micrometers respectively. Weighted t-test correlations showed no
statistical significance.
Citation
M.Med (Ophthalmology) ThesisSponsorhip
University of NairobiPublisher
Department of Medicine, University of Nairobi
Description
Master of Medicine Thesis