A C T A O P H T H A L M O L O G I C A V O L . 5 8 1 9 8 0

CENTRAL CORNEAL THICKNESS AND INTRAOCULAR TENSION

IN PATIENTS WITH ACROMEGALY

BY

THORKILD BRAMSEN. ANNE KLAUBER and PER BJERREI

In 27 patients with pituitary adenomas the central corneal thickness and the intraocular tension were measured. Thirteen of the patients were suffering from acromegaly, and in this group the central corneal thickness was 0.561 mm ? 0.035 (X 2 SD). In the 14 patients with pituitary adenomas but no acromegaly the central corneal thickness was 0.526 mrn t 0.030 (X t sn). This difference is statistically significant 0.01 > P > 0.001. In the 13 patients with acromegaly the intraocular tension measured by applanation was 16.9 mmHg ? 2.3 (3ik sn) and in the control group 14.7 mmHg k 2.4 (X t SD). This difference is statistically significant (0.05 > P > 0.02). When the applanation reading is corrected for the difference in the central corneal thickness, the patients suffering from acromegaly have an intraocular tension of 14.1 mmHg-, which is of the same magnitude as the tension in the patients without acromegaly.

Key roordc: acromegaly - central corneal thickness - pituitary adenoma - intraocular tension.

In adults growth hormone-producing pituitary adenomas often result in acro- megaly, characterized by growth of peripheral parts of the body, i.e. bones as well as soft tissues. Important to the general appearance is the thickening of the facial soft parts.

Received February 13, 1980.

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Thorkzld Brumtm, Annp Khuhcr and Ppr Blrrrr

Decrease of the acromegalic changes of the soft tissues is an important indicator of successful treatment. N o methods exist for measuring this. Growth hormone- analyses are of limited value, because the correlation between plasma growth hormone level and clinical activity of the disease is poor (Lindholm 1979). If the cornea takes part in the thickening of the soft tissues, measurement of the central corneal thickness (CCT), which can be performed with great accuracy, would possible be of importance in the diagnosis and the control of the acromegalic patient, Ehlers & Bramsen (1978) found in 45 conscripts a CCT of 0.510 mm k 0.027 (mean k SD).

Increased intraocular tension has been described with a high frequency in patients with acromegaly (Aren & Skanse 1955; Howard & English 1965). If the CCT increases with acromegaly, it would be assumed that the applanatory values will increase and thus, falsely indicate increased intraocular tension (Ehlers et al.

The purpose of this investigation has been to measure the CCT and the intraocular tension in patients with pituitary adenomas with and without acro- megaly.

1975).

Material and Methods

The material consists of 27 patients with pituitary adenomas verified by X-ray examination or operation. CCT was measured with a modified Haag-Streit pacho- meter as described by Ehlers & Sperling 1977.

The coefficient of variation of the CCT measurement is for a trained examinator about 1% (Olsen et a1 1980). The intraocular tension was measured by applanation tonometer as described by Goldmann. Measurements were performed by the two ophthalmological authors, and the mean value of the two eyes was used in the calculations. The examining ophthalmologists were unaware of the case records and the diagnosis. Obviously, acromegaly could often be identified at a glance. The participating neurosurgeon was ignorant of the CCT until the conclusion of the study.

Included were 13 patients with acromegaly, seven females and six males. The average age was 46.7 years ranging from 23 to 68 years. The duration of the disease varied from 1.5 to 17 years.

In the group of pituitary adenomas without acromegaly were included 14 patients, eight females and six males. The average age was 43.1 years ranging from 23 to 63 years. The duration of the disease was from 0.5 to 17 years.

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Cmtrul Corneal Thickne.Ts, Intruocnlar Tension and Acromegaly

with acromegaly (N = 13)

Tahlr I . CCT. applanation readings and corrigated applanation readings =

intraocular tension in patients with pituitary adenoma nit11 and without acromegaly.

without acromegaly (N = 14)

I Patients with pituitary adenoma

CCT mm f SD 0.561 -+ 0.035 0.526 f 0.030 Applanation readings mmHg ? SD 16.9 f 2.3 14.7 f 2.4

Corrigated applanation readings Intraocular tension mmHg f SD 14.1 f 2.3 14.2 f 2.4

Results

The result of the measurements of the CCT and the intraocular tension appear from Table I .

The difference in the CCT between the two groups is significant 0.01 > P > 0.001.

The difference in the direct applanation readings between the two groups is significant 0.05 > P > 0.02.

No difference in corrigated applanation readings is found between the two groups.

Discussion

The investigation has shown that in patients with acromegaly the CCT is increased compared to patients with pituitary adenomas without acromegaly, suggesting a hypertrophic effect of growth hormone on the corneal tissue.

The present investigation does not show which layers of the cornea are respons- ible for the increased CCT. At slitlamp examination and during the pachometer- measurements the cornea appeared normal, especially without any signs of oe- dema. Within both groups a considerable variation in the CCT was noted. In the acromegaly group this might be explained by different levels of endocrine activity. An investigation on this has been started. In the control group there are two

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Thorkzld Brrimsrn. Anne Kkaiihw nnd Prr B y r e

patients who are suspected of having acromegaly and where only a period of observation can decide the final diagnosis.

The investigation also demonstrated increased applanation values in patients with acromegaly compared to patients with pituitary adenomas without acromegaly.

As mentioned in the introduction, a connection has already been noticed between increased applanation readings and pituitary adenomas. Especially during the 1960’s this led to discussions (Godtfredsen 1968). Naturally patients may occur with both glaucoma simplex and acromegaly as independent diseases. The increased applanation readings in the acromegalic patients of this investigation are due to a misinterpretation of the measured tension values, as it has already been shown (Ehlers et al. 1975) that an increased CCT leads to higher applanatory values. If the applanation readings in this group corrected for the increased CCT, the acro- megaly-patients have a true intraocular tension of 16.9 mmHg - 2.8 mmHg = 14.1 mmHg, which is of the same normal magnitude as in the group without acro- megaly. The corresponding figures for patients with pituitary adenomas but no acromegaly were 14.7 mmHg-0.5 mmHg = 14.2 mmHg.

References

Aren A. & Skanse B. (1955) On non-inflammatory glaucoma in acromegaly. Art0 ophthnl.

Ehlers N., Bramsen T. & Sperling S. (1975) Applanation tonometry and central corneal

Ehlers N. & Sperling S. (1977) A technical improvement of the Haag-Streit pachometer. Artn

Ehlers N. & Bramsen T. (1978) Central thickness in corneal disorders. Actci ophthal. (Khh.) 56,

Godtfredsen E. (1968) Glaucoma and pituitary tumour. Artn ophthrcl. (Khh.J 46, 600-604. Howard G. M. & English F. P. (1965) Occurence of glaucoma in acroniegalics. Arch. Ophthnl.

LindholmJ. (1979) Assessment of pituitary function. Actn Nmrol. Scnnd. 59, I61 - 171. Olsen T., Nielsen C. B. & Ehlers N. (1980) On the optical measurements of corneal thickness.

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thickness. Actn vfihthnl. (Khh.) 53, 34-43.

ofihthal (Khh.) 55, 333-336.

4 12-4 16.

(Chicogo) 73, 765-7158.

Actn ofihthnl. (Kbh.) 58, 760-766.

Author’.i address:

T. Bramsen, Department of Ophthalmology, Aarhus Kommunehospital, DK-8000 h h u s C, Denmark.

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