Printer Friendly

Central corneal thickness in fuchs' uveitissyndrome/Fuchs uveit sendromunda santral kornea kalinligi.

Summary

Purpose: To investigate whether the central corneal thickness (CCT) values of uveitic eyes were different from those of nonuveitic eyes and of control subjects and whether the intraocular pressure (IOP) was associated with the CCT in patients with Fuchs' uveitis syndrome (FUS).

Material and Method: Fifty-one unilarerally involved FUS patients and 51 age- and gender-matched control subjects were included in the study. Complete ophthalmologic examinations and pachymetry measurements were performed. CCT and IOP values were compared between involved, uninvolved and control group eyes.

Results: The groups were age- and gender-matched. No significant difference was found between the mean CCT values of the involved (561.1 [+ or -] 43.7 [micro]m) and uninvolved (564.6 [+ or -] 45.7 [micro]m) eyes (p = 0.08). When compared with the control group (547.7 [+ or -] 36.9 [micro]m), only uninvolved eyes CCT was found to have significant difference (p = 0.04). The mean IOP was 14.4 [+ or -] 7.2 mmHg and 14.6 [+ or -] 3.4 mmHg in involved and uninvolved eyes of FUS patients, respectively. Elevated IOP or glaucoma was present in 13/51(25.5%) patients in the FUS group. The mean IOP (12.9 [+ or -] 2.4 mmHg) in the control group did not reveal any significant difference compared to FUS group.

Discussion: The chronic low-dose inflammation does not affect corneal thickness as much as an acute inflammation, and the IOP might be associated with CCT in FUS. (Turk J Ophthalmol 2013; 43: 225-8)

Key Words: Fuchs, uveitis, central corneal thickness, intraocular pressure

Ozet

Amac: Fuchs uveit sendromlu (FUS) hastalarin uveitik gozlerindeki merkezi kornea kalinlik (MKK) degerlerinin non- uveitik ve kontrol grubundan farkli olup olmadigini ve goz ici basinci (GIB) degerlerinin MKK ile iliskili olup olmadigini arastirmak.

Gerec ve Yontem: Tek tarafli tutulumu olan 51 FUS hastasi ile yas ve cinsiyet uyumlu 51 kontrol hastasi calismaya dahil edildi. Tam oftalmolojik muayene ve pakimetri olcumleri yapildi. Tutulumu olan, olmayan ve kontrol grup MKK ve GIB degerleri karsilasririldi.

Sonuclar: Gruplar yas ve cinsiyet acisindan uyumluydu. Tutulumu olan (561,1 [+ or -] 43,7 [micro]m) ve olmayan (564,6 [+ or -] 45,7 [micro]m) gozlerde ortalama MKK degerleri acisindan fark yokru (p = 0,08). Kontrol grubu (547,7 [+ or -] 36,9 [micro]m) ile karsilasririldiginda yalniz tutulum olmayan goz MKK degeri anlamli olarak farkliydi (p = 0,04). FUS hasralarinda ortalama GIB tutulum olan ve olmayan gozlerde sirasiyla 14,4 [+ or -] 7,2 mmHg ve 14,6 [+ or -] 3,4 mmHg idi. Kontrol grubu ortalama GIB (12,9 [+ or -] 2,4 mmHg) FUS grubu ile karsilastirildiginda anlamli farklilik yoktu.

Tartisma: Kronik dusuk dereceli enflamasyon kornea kalinligini akut enflamasyon kadar etkilememektedir ve FUS' da GIB ile MKK arasinda iliski olabilir. (Turk J Ophthalmol 2013; 43: 225-8)

Anahtar Kelimeler: Fuchs, uveit, merkezi kornea kalinligi, goz ici basinci

Introduction

Since first described by Ernst Fuchs (1) in 1906, the uveitic entity called Fuchs' uveitis syndrome (FUS) has dragged the attention of ophthalmologists. It is a chronic, low-grade, mainly anterior uveitis with varied degree of vitreous opacities, characteristic diffusely spread small to medium sized keratic precipitates (KPs), diffuse iris atrophy with or without obvious heterochromia and lack of posterior synechiae. Due to its silent course without acute exacerbations, patients mostly present with floaters or complications like cataract and glaucoma. (2,3)

The corneal thickness is a major parameter for corneal integrity and depends on endothelial barrier and pump functions. The effect of intraocular inflammation on corneal thickness was studied both in vitro (4,5) and in vivo. (6,7) MacDonald et al. (5) showed that anterior segment inflammation affects both endothelial barrier and pump functions leading to increased corneal thickness. Pillai et al. (7) studied the corneal endothelium in acute uveitis and have found a significant difference in cell size and density of the endothelium in the vicinity of KR Similarly, studies that were conducted to compare CCT values in acute and remission phase of Behcet's disease patients have found a significant difference in corneal thickness. (8,9)

The aim of this study was to investigate whether the CCT values of uveitic eyes were different from those of nonuveitic eyes and of age- and gender-matched normal individuals, and also, whether the intraocular pressure (IOP) was associated with the CCT in patients with FUS.

Materials and Methods

The study included 51 unilaterally involved patients diagnosed as FUS who were being followed at our Uvea and Behcet's Disease department and 51 age- and gender-matched control subjects who had undergone a daily outpatient examination. Subjects having bilateral uveitic involvement, corneal diseases, and history of contact lens wear or ocular surgery were excluded. All subjects were informed about the study and their consents were taken. The study adhered to the tenets of Declaration of Helsinki guidelines. The clinical diagnosis of FUS was made or confirmed by the same clinician. Clinical findings taken into consideration for the diagnosis of FUS were low-grade chronic anterior inflammation, diffuse iris atrophy with or without heterochromia, typical diffusely spread KPs, vitreous opacities, presence of posterior subcapsular cataract, lack of posterior synechiae and cystoid macular edema, resistance to steroid therapy, absence of acute exacerbations, and posterior inflammation. When several of these findings were present, the diagnosis was made as FUS, and no diagnostic examination was performed in most of the patients. All patients underwent detailed ophthalmic examination including best-corrected visual acuity on a Snellen chart, tonometry, slit-lamp biomicroscopy, and dilated fundus examination. The examinations and the measurements were performed between 9 and 11 a.m. by the same doctor to avoid diurnal and interobserver variations. Intraocular pressure was measured by non-contact tonometer (Reichert AT-555; Reichert Ophthalmic Instruments, NY, USA) without any topical anesthetic, and the average of 4 readings was recorded. CCT was measured by ultrasound pachymeter (Tomey Biopachymeter AL-1000; Tomey Corporation, Nagoya, Japan) under topical anesthesia and again the average of 4 consecutive readings was recorded. Patients in whom the IOP was >21 mmHg without any glaucomatous cupping and visual field defects were considered as elevated IOP Patients with IOP readings greater than 21 mmHg with glaucomatous cupping and visual field defects were diagnosed as having glaucoma. The statistical analysis was performed by SPSS 15.0, and p < 0.05 was accepted as statistically significant.

Results

The mean age was 35.7 [+ or -] 11.9 years in FUS patients and 36.3 [+ or -] 5.0 years in control subjects. The male to female ratio was 26/25 in FUS group and 25/26 in control group. The two groups were age- and gender-matched (independent-sample t-test, p = 0.75 and Mann-Whitney U-test, p = 0.84 respectively). In the FUS group, the inflammation was on the right eye in 62.7% of the patients. Mean values of involved and uninvolved eyes of FUS group and control group IOP and CCT values are shown in Table 1. The mean CCT values of the involved and uninvolved eye in the FUS group were 561.1 [+ or -] 43.7 [micro]m and 564.6 [+ or -] 45.7 [micro]m, respectively. There was no statistically significant difference between the CCTs of involved and uninvolved eyes (paired-sample t-test, p = 0.08). The mean right and left eye CCT values of the control group were 547.7 [+ or -] 36.9 [micro]m and 549.6 [+ or -] 37.2 [micro]m, respectively. Since there was a strong correlation between right and left eye values, the right eye CCT values of the control group were used for statistical analysis (Pearson's correlation test, r = 0.97 p = 0.00). Although the CCT values of both the involved and uninvolved eyes of FUS group were found to be higher than those of the control group, this difference was statistically significant only for the uninvolved eyes (independent-sample t-test, p = 0.09 and p = 0.04, respectively).

Since there was a significant correlation between right and left eye IOP values of the control subjects and FUS group, the right eye IOP values were used for statistical purposes (Pearson's correlation test, r = 0.731 p = 0.00 and r = 0.421 and p = 0.00, respectively). There was no statistically significant difference between the mean IOP values of FUS group (14.4 [+ or -] 7.2 mmHg) and the control group (12.9 [+ or -] 2.4 mmHg) (independent sample t-test, p = 0.15). Elevated IOP or glaucoma was present in 13/51 (25.5%) patients in FUS group but in none of the control group.

In the FUS group, the mean IOP was 14.4 [+ or -] 7.2 mmHg and 14.6 [+ or -] 3.4 mmHg in involved and uninvolved eyes, respectively. Although statistically insignificant, the mean IOP in the uninvolved eyes was slightly higher than that of the involved eyes (paired-sample t-test, p = 0.89). Number of patients having higher IOP readings in the uninvolved eye was 28 (55%).

The mean CCT of 13 FUS patients with elevated IOP or glaucoma was 556.2 [+ or -] 52.9 [micro]m, while it was 562.8 [+ or -] 40.7 [micro]m in patients with normal IOR This difference was not statistically significant (Mann-Whitney U-test, p = 0.56).

Discussion

Fuchs' uveitis syndrome is a unique condition characterized by chronic, low-grade and mostly asymptomatic ocular inflammation leading to complications like cataract, glaucoma, or severe vitreous opacities. Although the diagnosis of FUS is entirely clinical, it is often misdiagnosed mostly because of the vitreous involvement which is not commonly recognized as an association with FUS. (3,10-12)

The etiology of this particular entity is still unclear. Infectious etiologies like Herpes simplex virus, (13) toxoplasma-toxocarahistoplasma (3) and rubella, (14) hereditary associations (15,16) and neurogenic dysfunction theories (17,18) are being argued to clarify the underlying pathology.

The effect of intraocular inflammation on corneal endothelium has been studied both in experimental (4,5) and in clinical studies (6,8,9) in an experimental model, MacDonald et al. (5) injected serum bovine albumin intravitreally and created an ocular inflammation. They showed that ongoing inflammation causes a breakdown in apical junctions of corneal endothelium leading to compromised barrier function. They also detected a breakdown in endothelial pump sites. These two conditions have resulted in an increment of the corneal thickness. Different studies have also demonstrated polymegathism and polymorphism of endothelial cells in specular microscopic examinations. (6,7,19,20) The endothelial changes that occur in the active inflammatory phase are believed to be temporary and return to normal after the inflammation subsides.

Ozdamar et al. (8) and Evereklioglu et al. (9) studied CCT in Behcet's disease patients. Both studies have found that the CCT values of patients with active inflammation are greater than inactive Behcet's disease and control group. The mean CCT value of the active Behcet's disease patients was found to be approximately 30-40 [micro]m thicker. They also emphasized that this CCT increase was temporary and returned to normal values as the active inflammation subsided.

Differently from Behcet's disease, inflammation is always lowgrade and chronic in FUS. One of the characteristic clinical features of this typical inflammatory pattern is the presence of diffusely spread, fine, stellate or medium-sized round non-pigmented KPs. (2,3,12) As we mentioned before, KPs are blamed for changing the endothelium metabolism. (7) To see if the corneal endothelium is affected by the chronic inflammation due to FUS, we evaluated CCT values of patients with this specific uveitic entity. As it is directly influenced by the endothelial function, CCT is an ideal parameter to evaluate the endothelial changes. (22,23) To the best of our knowledge, this study is the first and only study to evaluate CCT in FUS. Since we excluded bilateral involvement, we had chance to compare the involved and uninvolved eyes in same patient which neutralizes the subjects variations. In our study, the mean CCT of the involved eye was 561.1 [+ or -] 43.7 [micro]m and in the uninvolved eye was 564.6 [+ or -] 45.7 [micro]m. Whereas the mean CCT value of the control group was 547.7 [+ or -] 36.9 [micro]m. The CCT values of patients with FUS both in involved and uninvolved eyes were higher than those of the control subjects. This difference was significant only for the uninvolved eyes. These results may be considered as evidence showing that the chronic inflammation in FUS does not disturb the endothelial functions as much as in acute inflammatory conditions and that the cornea is thicker than the normal population probably due to hereditary factors.

Elevated IOP or glaucoma is considered to be the most serious problem of FUS. (2) Its incidence is reported to vary between 6.3% and 59% in a review by Jones. (21) Elevated IOP has been reported in 12.7% of patients in Tugal-Tutkun et al.'s (12) study and in 24% in Norrsell and Sjodell's (2) study in accordance with our result which is 25.5%. The thickness of the cornea is closely related to IOP measurements with thicker cornea leading to higher IOP readings. Ocular Hypertension Treatment Study (OHTS) had revealed that CCT is also an independent risk factor for glaucoma conversion of ocular hypertension. (24) In the meta-analysis of 80 studies, Doughty and Zaman (25) reported that 20 [micro]m change in CCT corresponded to 1 mmHg change in IOR Although statistical significance appeared only for the uninvolved eyes of FUS patients, the mean CCT of FUS patients in both involved and uninvolved eyes were approximately 20 pm thicker than the control group, which may result in approximately 1 mmHg higher IOP readings. The mean IOP of involved (14.4 [+ or -] 7.2 mmHg) and uninvolved eyes (14.6 [+ or -] 3.4 mmHg) were approximately 1.5 mmHg higher when compared to the mean IOP of the control group (12.9 [+ or -] 2.4 mmHg). The higher IOP readings in FUS patients might be attributable to their thicker corneas. Although elevated IOP is an important problem in FUS and is observed in 25.5% of our patients, interestingly, the mean IOP was lower in most of the involved eyes (55%) when compared with the uninvolved eyes. Bouchenaki and Herbort (10) had reported similar finding regarding the IOP difference between healthy and affected eyes of their FUS patients. The mean IOP was lower in 50% of affected eyes in their series.

As a conclusion, although an acute ocular inflammation affects endothelial functions and thus the corneal thickness as reported in previous studies, (4-6,8,9) a chronic inflammation does not affect the corneal endothelial functions and corneal thickness as much as the acute ocular inflammatory conditions. However, higher CCT readings in FUS patients may result in high IOP measurements.

DOI: 10.4274/tjo.43.66934

References

(1.) Fuchs E. Ueber komplikationen der heterochromie. Z Augenheilkd. 1906;15:191-212.

(2.) Norrsell K, Sjodell L. Fuchs' heterochromic uveitis: a longitudinal clinical study. Acta Ophthalmol. 2008;86:58-64.

(3.) Mohamed Q, Zamir E. Update on Fuchs' uveitis. Curr Opin Ophthalmol. 2005;16:356-63.

(4.) Behar-Cohen FF, Salvoldelli M, Parel JM, et al. Reduction of corneal edema in endotoxin induced uveitis after application of L-NAME as nitric oxide synthase inhibitor in rats by iontophotesis. Invest Ophthalmol Vis Sci. 1998;39:897-904.

(5.) MacDonald JM, Geroski DH, Edelhauser HF. Effect of inflammation on the corneal endothelial pump and barrier. Curr Eye Res. 1987;6:1125-32.

(6.) Olsen T. Transient changes in specular appearance of the corneal endothelium and in corneal thickness during anterior uveiris. Acta Ophthalmol (Copenh). 1981;59:100-9.

(7.) Pillai CT, Dua HS, Azuara-Blanco A, Sarhan AR. Evaluation of corneal endothelium and keratic precipitates by specular microscopy in anterior uveitis. Br J Ophthalmol. 2000;84:1367-71.

(8.) Ozdamar Y, Berker N, Ertugrul G, Gurlevik U, Karakaya J, Ozkan SS. Is there a change of corneal thickness in uveitis with Behcet disease? Cornea. 2010;29:1265-67.

(9.) Evereklioglu C, Er H. Increased corneal thickness in active Behcet's disease. Eur J Ophthalmol. 2002;12:24-9.

(10.) Bouchenaki N, Herbort CP. Fuchs' Uveitis: Failure to associate vitritis and disc hyperfluorescence with the disease is the major factor for misdiagnosis and diagnostic delay. Middle East Afr J Ophthalmol. 2009;16:239-44.

(11.) Fearnley IR, Rosenthal AR. Fuchs' heterochromic iridocyclitis revisited. Acta Ophthalmol Scand. 1995;73:166-70.

(12.) Tugal-Tutkun I, Guney-Tefekli E, Kamaci-Duman F, Corum I. A cross sectional and longitudinal study of Fuchs Uveitis Syndrome in Turkish patients. Am J Ophthalmol. 2009;148:510-5.

(13.) Barequet IS, Li Q, Wang Y, O'Brien TP, Hooks JJ, Stark WJ. Herpes simplex virus DNA identification from aqueous fluid in Fuchs heterochromic iridocyclitis. Am J Ophthalmol. 2000;129:672-3.

(14.) Quentin CD, Reiber H. Fuchs heterochromic cyclitis: rubella virus antibodies and genome in aqueous humor. Am J Ophthalmol. 2004;138:4654.

(15.) Makley TA. Heterochromic cyclitis in identical twins. Am J Ophthalmol. 1956;41:768-72.

(16.) Loewenfeld IE, Thompson HS. Fuchs's heterochromic cyclitis: A critical review of the literarure. II. aetiology and mechanism. Surv Ophthalmol. 1973;18:2-61.

(17.) Melamed S, Lahav M, Sandbank U, Yassur Y, Ben-Sira I. Fuch's hererochromic iridocyclitis: an electron microscopic study of the iris. Invest Ophthalmol Vis Sci. 1978;17:1193-9.

(18.) Regenbogen LS, Naveh-Floman N. Glaucoma in Fuchs' heterochromic cyclitis associated with congenital Horner's syndrome. Br J Ophthalmol. 1987;71:844-9.

(19.) Olsen T. Changes in the corneal endothelium after acute anterior uveitis as seen with the specular microscope. Acta Ophthalmol (Copenh). 1980;58:250-6.

(20.) Brooks AM, Grant G, Gillies WE. The use of specular microscopy to investigate unusual findings in the corneal endothelium and its adjacent structures. Aust N Z J Ophthalmol. 1988;16:235-43.

(21.) Jones NP. Fuchs' heterochromic uveitis: an update. Surv Ophthalmol. 1993;37:253-72.

(22.) Ehlers N, Hjortdal J. Corneal thickness: measurement and implications. Exp Eye Res. 2004;78:543-8.

(23.) Bourne WM, McLaren JW. Clinical responses of the corneal endothelium. Exp Eye Res. 2004;78:561-72.

(24.) Gordon MO, Beiser JA, Brandt JD, et al. The Ocular Hypertension Trearment Study: Baseline factors that predict the onset of primary open-angle glaucoma. Arch Ophthalmol. 2002;120:714-20.

(25.) Doughty MJ, Zaman ML. Human corneal thickness and its impact on intraocular pressure measures: a review and meta-analysis approach. Surv Ophthalmol. 2000;44:367-408.

Pinar Cakar Ozdal, Alper Yazici *, Ufuk Elgin, Faruk Ozturk Ulucanlar Eye Training and Research Hospital, Ankara, Turkey

* Balikesir University Faculty of Medicine, Department of Ophthalmology, Balikesir, Turkey

Address for Correspondence/Yazisma Adresi: Pinar Cakar Ozdal MD, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey Gsm: +90 530 349 49 75 E-mail: pinarozdal@hotmail.com

Received/Gelis Tarihi: 31.01.2013 Accepted/Kabul Tarihi: 01.03 2013
COPYRIGHT 2013 Galenos Yayinevi Tic. Ltd.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2013 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Original Article/Ozgun Arastirma
Author:Ozdal, Pinar Cakar; Yazici, Alper; Elgin, Ufuk; Ozturk, Faruk
Publication:Turkish Journal of Ophthalmology
Article Type:Report
Date:Jul 1, 2013
Words:3071
Previous Article:Comparison of pain response of patients undergoing panretinal photocoagulation for proliferative diabetic retinopathy: 532 nm standard laser vs....
Next Article:Amniotic Membrane Transplantation in Herpetic Keratitis and Bacterial Keratitis/ Herpetik Keratit ve Bakteriyel Keratitlerde Amniyotik Membran...
Topics:

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters