The Egyptian Journal of Hospital Medicine (January 2018) Vol. 70, Page

Transcription

1 The Egyptian Jounal of Hospital Medicine (Januay 2018) Vol. 70, age Coelation between Cental Coneal Thickness and Degee of Myopia Mostafa A, Mohamed M, Mohamed M. Al Hussein Univesity Hospital and Nou Al Hyaa Eye Hospital, Caio. Coesponding autho: Momen Mohamed, ABSTRACT Aim of the wok: this study aimed to detemine the elationship between cental coneal thickness (CCT) and myopia. Methods: one hunded and eight (108) Egyptian subjects wee included in this study. They wee not pesenting with any eye disease and had neve undegone eye sugey. The total numbe of subjects meeting the inclusion citeia was 108 (216 eyes) 87 wee myopes and 21 wee emmetope. They wee categoized into two main goups: myopic goup (Goup I) and the contol goup (Goup II). The CCT was measued with the pentacam. Results: the pesent study compised 59 males (54.6 %) and 49 females (45.4%). Thei age anged between 19 and 58 yeas. The mean CCT was ight eye and left eye in goup Ia, ight eye and left eye in goup Ib, ight eye and left eye in goup Ic, and ight eye and left eye in the contol goup (Goup II). Conclusion: this clinical study showed that thee was no diffeence in CCT between emmetopic and myopic eyes. CCT did not coelate with the degee of myopia. Keywods: cental coneal thickness, myopia pachymety. INTRODUCTION The conea is a tanspaent, a vascula tissue that measues mm hoizontally and mm vetically. The conea along with sclea foms the outemost coat of the eyeball, it is a complex stuctue has a potective ole; it is esponsible fo about thee quates of the optical powe of the eye (1).It contibutes 74% o dioptes (D) of the total dioptic powe of a nomal human eye. Its efactive index is The nomal conea is fee of blood vessels. Fo its nutition, the conea depends on glucose diffusing fom the aqueous humo and oxygen diffusing though the tea film. In addition, the peipheal conea is supplied with oxygen fom the limbal ciculation. The conea has one of the body s highest densities of neve endings and the sensitivity of the conea is 100 times that of the conjunctiva. The conea is composed of six layes; which ae epithelium, Bowman s laye, stoma, Dua s laye, Descemet s membane and endothelium (2). The nomal thickness of the conea vaies fom cental to peipheal limbus and it is anging fom 0.7 to 0.9 mm at the limbus and fom 0.49 mm to 0.6 mm at the cente. Cental coneal thickness (CCT) is an impotant indicato of coneal health status. As an estimate of the coneal baie and endothelial function, CCT is an essential tool in the assessment and management of coneal disease (3). Moeove, CCT is a measue of coneal igidity and consequently has an impact on the accuacy of intaocula pessue measuement by applanation tonomety. A study had demonstated that thicke coneas with geate igidity may offe a geate esistance when subjected to applanation, esulting in atificially highe intaocula pessue eadings (4). In addition, with the development of coneal efactive sugey pocedues, CCT values ae of enomous impotance duing the peopeative evaluation of the patients as they influence the decision whethe o not to pefom sugey, the type of ecommended pocedue and ate of postopeative complications (5).Coneal pachymety is the pocess of measuing the thickness of the conea. It can be done by using contact methods such as ultasound and confocal micoscopy o non-contact methods such as optical biomety with a single Scheimpflug camea (such as the Oculus entacam o Siius), Dual Scheimpflug (eg, Galilei), coheence tomogaphy (Visante, ivue, o othes), o optical coheence pachymety (with obscan) (3). Myopia is a common efactive eo especially in Asian counties undegoing apid development. Myopia pevalence could be as high as 95% in medical school students. Myopic changes of the eyes included elongated axial length, deepe 109 Received: 02/10/2017 DOI: / Accepted: 12/10/2017

2 Coelation between Cental Coneal Thickness anteio chambe, thinne etina with lattice changes and highe pevalence of etinal detachment, deceased chooid ciculation, as well as deceased scleal thickness and elasticity (6). Kobayashi et al. (7) found lage vaiation in axial length in highly myopic childen. This vaiation might imply that the cause of high myopia might not only be axial elongation, but also some othe congenital poblems which could affect othe optical component, such as the conea. ATIENTS AND METHODS One hunded and eight (108) Egyptian subjects wee included in this study. They wee not pesenting with any eye disease and had neve undegone eye sugey. The total numbe of subjects meeting the inclusion citeia was 108 (216 eyes) 87 wee myopes and 21 wee emmetope. They wee divided into two main goups: Myopic goup (Goup I) and the contol goup (Goup II). The myopic goup (goup I) was subdivided accoding to the degee of myopia into 3 subgoups: Goup Ia: 52 subjects with myopia less than 5.00 D. Goup Ib: 20 subjects with myopia fom 5.00 D to less than D. Goup Ic: 15 subjects with myopia fom to D. aticipants undewent a complete ophthalmologic examination including visual acuity, slit-lamp examination, fundoscopy, IO and cycloplegic efaction. The CCT was measued with the pentacam. All examinations and investigations wee done at Al Hussein Univesity Hospital and Nou Al Hyaa Eye Hospital, Caio. The study was done afte appoval of ethical boad of Al-Azha univesity. Statistical analysis Data wee collected, tabulated, statistically analyzed using an IBM pesonal compute with Statistical ackage of Social Science (SSS) vesion 20 whee the following statistics wee applied. a- Desciptive statistics: in which quantitative data wee pesented in the fom of mean ( ), standad deviation (SD), ange, and qualitative data wee pesented in the fom numbes and pecentages. b- Analytical statistics: used to find out the possible association between studied factos and the tageted disease. RESULTS The total numbe of subjects meeting the inclusion citeia was 108 (216 eyes). Eighty-seven subjects wee myopes and 21 subjects wee emmetopes. They wee categoized into 2 main goups: myopic goup (Goup I) and emmetopic goup (Goup II). The myopic goup (Goup I) was futhe subdivided accoding to the degee of myopia into 3 subgoups: Goup Ia: 52 subjects with myopia less than 5.00 D. Goup Ib: 20 subjects with myopia fom 5.00 D to less than D. Goup Ic: 15 subjects with myopia fom to D. The study compised 59 males (54.6 %) and 49 females (45.4 %) (Table 1 and figue 1). Thei age anged fom 19 to 58 yeas with a mean of 30.7±9.46. (Table 2 and figue 2). Table 1: sex distibution among the studied goups (n=108) Contol Total Chi Studied vaiables Goup Ia Goup Ib Goup Ic goup (N=108) squae (N=52) (N=20) (N=15) (N=21) value No. % No. % No. % No. % No. % Gende - Male Female This table showed that thee was no significant diffeence between the studied goups egading thei sex ( value >0.05). 110

3 Mostafa A et al. Goup Ia Goup Ib Goup Ic Table 2: mean age of the studied goups (N=108) Goup Ia Goup Ib Studied (N=52) (N=20) vaiables Figue 1: sex distibution among the studied goups Goup Ic (N=15) Contol goup (N=21) Kuskal Wallis test value Age / yeas 31.2± ± ± ± This table showed that thee was no significant diffeence between studied goups egading thei age ( value >0.05) Goup Ia Goup Ib Goup Ic Figue 2: mean age of the studied goups The mean efaction among the studied goups is shown in table 3 Table 3: mean efaction among the studied goups (N=108): Goup Ia Goup Ib Goup Ic Refaction (N=52) (N=20) (N=15) Contol goup (N=21) Kuskal Wallis test value Right eye -2.91± ± ± ± ** Left eye -3.06± ± ± ± ** **highly significant This table showed that thee was highly significant diffeence between studied goups egading thei eos of efactions in both eyes (Table 3) ( value < 0.001). 111

4 Coelation between Cental Coneal Thickness The mean CCT is shown in table 4 and figue 3 Table (4): mean CCT among the studied goups (n=108) Goup Ib Goup Ic Goup Ia (N=52) CCT (N=20) (N=15) Contol goup (N=21) ANOVA value Right eye 538.2± ± ± ± Left eye 536.3± ± ± ± This table showed that thee was no significant diffeence between the studied goups egading thei CCT in both eyes (Table 4) ( value >0.05). Goup Ia Goup Ib Goup Ic Figue 3: mean CCT among the studied goups The coelation between eo of efaction and CCT in myopic subjects was shown in table 5. Table 5: coelation between eo of efaction and CCT in myopic patient (n=87) Refaction Right Left Studied vaiables CCT This table showed that thee was no coelation between eo of efaction in both eyes and CCT in myopic patient (Table 5). The coelation between eo of efaction and age in myopic subjects is shown in table 6. Table 6: coelation between eo of efaction and age in myopic patient (n=87) Refaction Right Left Studied vaiables Age This table showed that: thee was no coelation between eo of efaction in both eyes and age of myopic patient (Table 6). The coelation between CCT and age in myopic subjects is shown in table

5 Mostafa A et al. Table 7: coelation between CCT and age in myopic patient (n=87) CCT Studied Right Left vaiables Age This table shows that thee was no coelation between CCT in both eyes and age of myopic patient (Table 7). DISCUSSION The pesent study compised 59 males (54.6 %) and 49 females (45.4%). Thei age anged between 19 and 58 yeas. The mean CCT was ight eye and left eye in goup Ia, ight eye and left eye in goup Ib, ight eye and left eye in goup Ic and ight eye and left eye in the contol goup (Goup II). The esults of the pesent study evealed no statistical diffeence between CCT of myopes and emmetopes. Also, no statistical diffeence was found between CCT of the thee myopic subgoups. Results of the cuent study agee with those of Liu and flugfelde (7), they concluded that cental coneal pachymety was coelated with the mean manual keatometic measuement, but no coelation was noticed between CCT and myopia in contact lens weaes. Neithe did the CCT coelate with the axial length, age, sex, hoizontal coneal diamete o efaction in ice's seies (8). In addition, Cho and Lam (9) found that CCT deceased with inceasing age, but not with efactive eo o coneal cuvatue. In the pesent study thee was no statistically significant diffeence elated to the age. The effect of efactive status on CCT had been epoted by many investigatos. Howeve, the esults of these epots wee conflicting. Some found that myopic subjects have a thicke CCT, othes epoted thinne CCT, while yet othes found no coelation between CCT and myopia. Theefoe, the elationship between the degee of myopia and CCT was inconclusive in a pevious study (10). The diffeent esults in a pevious study might be explained by any of the following: diffeent citeia fo inclusion and exclusion, influence of genetic and acial diffeences, influence of contact lens weaing, and diffeent devices and methods used fo assessment of the CCT and might be un-expeienced obseves. Also, diffeent sample sizes in the study may affect the esults. The eyeball elongates duing axial myopia pogession. This pogession not only makes the globe longe but also makes the sclea thinne, involving the posteio segment moe significantly. Also, thee ae dimensional changes in the anteio segment duing myopia pogession, but they ae less documented (6). CONCLUSION In the pesent study, the CCT showed no significant change with myopes and no statistically significant diffeence in CCT between myopes and emmetopes. Theefoe, the gowth alteation in ocula tunics of myopic eyes does not involve the coneal thickness which is of benefit fo most of coneal efactive sugeies. REFERENCES 1. Dua, McKee HD, Iion LC et al. (2013):Human coneal anatomy edefined: a novel pe-descemet laye (Dua's laye). Ophthalmology,120: Kanski B(2016): Clinical Ophthalmology: A Systemic Appoach. 8 th ed. Elsevie; China. p Huang SJ(1993): Ealy change of visual function in high myopia measued and analyzed by octopus automated peimete. Nippon Ganka Gakkai Zasshi, 97: Wang SY, Melles R and Lin SC(2014): The impact of cental coneal thickness on the isk fo glaucoma in a lage multi ethnic population. J. Glaucoma, 23: asad A and Fy K(2011):Relationship of age and efaction to cental coneal thickness: Conea Jounal, 30: Cutin BJ(1985): Ocula findings and complications In: Basic Science and Clinical Management.The Myopias.. Hape and Row: hiladelphia, pp: Liu Z and flugfelde SC (2000): The effects of longtem contact lens wea on coneal thickness, cuvatue, and suface egulaity. Ophthalmology, 107: ice FW, Kolle DL and ice MO(1999): Cental coneal pachymety in patients undegoing lase in situ keatomileusis. Ophthalmology,106: Cho and Lam C (1999): Factos affecting the cental coneal thickness of Hong Kong Chinese. Cu. Eye Res., 18: Fam HB, How AC, Baskaan M et al. (2006): Cental coneal thickness and its elationship to myopia in Chinese adults. B. J. Ophthalmol., 90: