Pakistan Oculoplastic Association of Pakistan

Collaborative Research

“Normal Range of Exophthalmometric values in Pakistani Population”

Objectives

To determine the normal Exophthalmometric value for Pakistani population.
To calculate mean “Inter-orbital distance” (IOD) for Pakistani population.

Introduction

Protrusion of eyes with reference to lateral orbital margin of an individual is called “Exophthalmometric Value” (EV). Normal EV depends upon multiple factors including age, gender, race & ethnic background, etc.

Multiple cross sectional studies have been performed in different parts of the world on different ethnic background individuals and variations in EVs noted. Mean EV for Asians is 14.4 ± 2.5mm, for white Americans is 16.5mm, black Americans is 18.5mm, for Sri Lankans is 15.82 ± 2.73mm and for India it is 15 ± 6mm in males and 16 ± 6mm in females7. From these studies it is clear that there is no standard uniform normal value for Exophthalmometry. Rather each race and ethnic group should develop its own normative data to calculate EV. In the majority of reports from different ethnic backgrounds, the relative protrusion value between two eyes is not more than 2 mm. Therefore, we agree with other researches that relative ocular protrusion value of up to 2 mm in the absence of other pathological findings may have little clinical significance; on the other hand, an asymmetry of more than 2 mm should be noted during medical check-ups. Meanwhile, while performing Hertel's Exophthalmometry, as a part of this procedure, we will also be calculating the IOD for normal Pakistani population.

Till now to our knowledge, no study has been done in Pakistan to determine normative data of Exophthalmometry and IOD. Therefore, Pakistan Oculoplastic Association (POA) has decided to determine normal EVs for our population.

Rationale of Study

At present no normal EV reference is available for Pakistani population due to which proptosis may be over/under-diagnosed. This study will provide normal reference EV for our own population. The Exophthalmometric Values (EVs) obtained can either serve as a diagnostic basis or be used to monitor the progress of orbital disease via serial measurements12. Similarly, normal IOD of Pakistani population will be determined in this study which will provide a baseline in various maxillofacial and oculoplastic procedures.