Clinical significance of central corneal thickness and comparison of central corneal thickness measurements methods

Abstract

Significance of central corneal thickness has been increasing in ophthalmology practice. It is an important clinical evaluation tool especially prior to refractive surgery and in diagnosis of glaucoma and keratoconus. Refractive surgery is planned according to preoperative central corneal thickness measurements. Besides, in order to determine actual intraocular pressure, central corneal thickness is measured and corrected eye pressure is obtained. Today, devices used in measurement of central corneal thickness do the measurement according to two principles. First and relatively older method is ultrasonic method. Optic method is the second and more recent method. In daily practice, the most commonly used clinical method in measurement of central corneal thickness is ultrasound pachymeter. However, this measurement technique requires contact between cornea and probe and gives thinner measurement results compared to the methods that use optic principle. Recently, several technologic methods based on optics have been put in use; they provide advantages of non-contact technique and objective determination of central corneal thickness. Of these methods, most commonly used include Specular Microscopy, Optical coherence tomography, Laser Doppler Interferometry, Optical low coherence reflectometry pachymetry, Optic based topographic mapping (also called screening section pachymetry) and Pentacam. In this article, it was aimed to evaluate importance of central corneal thickness in clinical use and compare measurement methods. J Clin Exp Invest 2014; 5 (1): 153-158

Keywords

• Central corneal thickness, glaucoma, refractive surgery, ultrasound pachymetry, optical method

Santral kornea kalınlığının klinik önemi ve santral kornea kalınlığı ölçüm yöntemlerinin karşılaştırılması

Öz

Santral kornea kalınlığının önemi oftalmoloji pratiğinde zaman geçtikçe artmaktadır. Bilhassa refraktif cerrahi öncesinde, glokom ve keratokonus tanısının konulması gibi klinik durumlarda önemli bir klinik değerlendirme aracıdır. Özellikle, refraktif cerrahi rutin olarak operasyon öncesi santral kornea kalınlığı ölçümüne göre planlanmaktadır. Ayrıca intraoküler basıncın doğru tespit edilebilmesi için de santral kornea kalınlığı ölçülüp düzeltilmiş göz tansiyonu belirlenir. Günümüzde santral kornea kalınlığı ölçümünde kullanılan aletler iki prensibe göre ölçüm yapmaktadır. Birinci ve nisbeten daha eski bir yöntem olan ultrasonik yöntem, ikinci ve daha yeni bir yöntem olan optik yöntemdir. Pratikde SKK ölçülmesinde en sık kullanılan klinik yöntem ultrason pakimetresidir. Ancak bu ölçüm yöntemi, kornea-prob teması gerektirmektedir ve kornea yüzeyindeki mekanik basınçtan dolayı optik prensip ile ölçüm yapan yöntemlere göre daha ince ölçüm değerleri vermektedir. Son yıllarda, non-kontakt teknik ve santral kornea kalınlığının objektif belirlenmesi avantajlarını sunan optik temele dayanan birçok teknolojik yöntemler kullanılmaya başlanmıştır. Bu yöntemlerin günümüzde en çok kullanılanları ise speküler mikroskobi, optik koherens tomografi, lazer doppler interferometri, optik düşük koherens reflektometri pakimetresi, optik temelli topografik haritalama sistemi ya da diğer adıyla tarayıcı kesit pakimetre ve pentacam olarak sıralanabilir. Bu makalede santral kornea kalınlığının klinik kullanımda öneminin anlaşılması ve ölçüm yöntemlerinin bilinmesi amaçlanmıştır.

Anahtar Kelimeler

• Santral kornea kalınlığı, glokom, refraktif cerrahi, ultrason pakimetri, optik yöntem

Kaynakça

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