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Relationship between Central Corneal Thickness and Severity of Open Angle Glaucoma using Optical Coherence Tomography

Original article



Central  corneal  thickness  plays  a  major  role  in  the  management  of  many  types  of glaucoma. Therefore, our aim is to determine the relationship between the severity of glaucoma  measured  by  optical  coherence  tomography  (OCT)  and  central  corneal thickness (CCT) among normal tension and high tension glaucoma patients. This is an observational  cross  sectional  study  on  190  patients  carried  out  in  Universiti Kebangsaan  Malaysia  Medical  Centre  (UKMMC).  Three  groups  of  patients  were identified;  60  normal  tension  glaucoma  (NTG),  61  primary  open  angle  glaucoma (POAG)  and  69  control.  Patients  were  identified  based  on  the  glaucomatous  visual field  changes  and  previous  record  of  intraocular  pressure  before  treatment.  Visual acuity  and  intraocular  pressure  measurements  were  recorded.  Specular  microscope was used to measure the CCT and the severity of glaucoma was evaluated objectively based  on  the  retinal  nerve  fibre  layer  (RNFL)  thickness  using  optical  coherence tomography.  Results  showed  NTG  patients  had  significantly  thinner  cornea, 503.07±32.27µm  compared  to  the  control  group,  517.45±31.74  µm  (p=0.012). However,  there  was  no  significant  difference  between  the  CCT  of  POAG  and  NTG groups (p=0.386).Retinal nerve fibre layer (RNFL) thickness was significantly different between  the  glaucoma  and  the  control  groups  (p<0.05  in  all  quadrant).  However, correlation between CCT and severity of RNFL thinning was only found for the POAG group  but  not  for  the  NTG  group.  (mean  RNFL  and  superior  quadrant  RNFL; r=0.251,0.401) . This study demonstrated the correlation between CCT and severity of glaucoma in  POAG  patients but  not for the  NTG group. Therefore, CCT is related to the severity of POAG-related visual loss.