Fixation and its role in the causation, laterality and location of pterygium: a study in amblyopes and non-amblyopes

Abstract

Aim To evaluate the role of fixation in causing pterygium and determining its laterality and location. Methods This is a prospective, observational, case-control study. Cases were defined as patients with primary pterygium who had unilateral amblyopia with eccentric fixation. Controls were age-matched patients with primary pterygium, but without amblyopia and eccentric fixation. All patients underwent complete ocular, orthoptic, and systemic examination and a detailed risk-factor assessment (latitude of residence, exposure to sunlight, sand, and a high-reflectance environment). The role of fixation in the causation, laterality and location of pterygium was evaluated. Fisher's exact test, the unpaired t-test, and odds ratio (OR) were carried out to determine the significance of the observations. Results The mean age of subjects was 47.1 ± 5.25 years in cases (n ¼ 107) and 48.2 ± 4.75 years in controls (n ¼ 310; P ¼ 0.78). As far as known risk factors were concerned, both groups were evenly matched. Among the cases, 88 (82.2%) patients demonstrated suppression of the amblyopic eye and 19 (17.8%) patients had abnormal retinal correspondence (ARC). Patients with suppression had a unilateral pterygium in the better (fixating) eye, whereas those with ARC had bilateral pterygia. Among the controls, 192 (61.9%) eyes had bilateral pterygia and 118 (38.1%) eyes had unilateral pterygium. In controls, the dominant eye had a higher prevalence of pterygium. All patients in both groups had a nasal pterygium. Pterygium and fixation were strongly associated (P ¼ 0.007; Fisher's exact test; OR À15.98; P ¼ 0.008). Conclusion Fixation appears to have an important role in causing pterygium and determining its location and laterality.

Pathophysiology of ocular surface squamous neoplasia

“…2 ) ( Waddell et al., 2006 ). A similar observation was made of pterygia in India where all the lesions in a study of 427 participants were nasal ( Sudhalkar, 2012 ). This is the area with the highest concentration of limbal epithelial crypts ( Shanmuganathan et al., 2007 ).…”

“…The clinical presentation of ocular surface dysplastic and neoplastic diseases provides clues to the pathophysiology of OSSN. Firstly, OSSN, pterygium, pingueculae, climatic droplet keratopathy and actinic keratosis are usually located within the interpalpebral fissure, the space between the open upper and lower eyelid that is exposed to UV radiation ( Waddell et al., 2006 , Sudhalkar, 2012 , Shields et al., 2004 , Gray et al., 1992 ). Secondly, most OSSN lesions arise from the limbus particularly the nasal quadrant ( Fig.…”

Occupational Exposure to Solar Radiation at Different Latitudes and Pterygium: A Systematic Review of the Last 10 Years of Scientific Literature

“…Further limitations may regard other occupational factors possibly relevant for pterygium development: as stated in the Methods section, we did not consider in this review studies investigating occupational artificial UV exposure, as in example in welding activities [ 5 , 8 , 51 , 52 ]. Furthermore, there are possibly other work-related factors associated with chronic corneal and conjunctival irritation that may be considered in pterygium etiology [ 2 , 3 , 4 , 53 , 54 ], including repeated occupational eye injuries, quite frequent in outdoor workers [ 55 , 56 ], e.g., in case of eye trauma with penetration of dusts in the eye [ 57 ], especially considering that outdoor work may be performed in a windy/sandy environment [ 47 , 58 ]: these factors were not adequately considered in the reviewed studies, and their role may deserve further investigations.…”

“…The lesion occurs often bilaterally, although with asymmetric development [ 3 ]. Even in cases of mono-laterality, pterygium is frequently associated to an initial degeneration of the contralateral conjunctival epithelium, without involvement of the cornea: the pinguecula [ 4 ].…”

Pterygium: are we any closer to the cause?

“…The prevalence of pterygium increases with proximity to the equator where there is prolonged exposure to ultraviolet light. In addition, pterygium occurs more commonly among those who work in a high-reflectance outdoor environment (among concrete for example) 8. The hypothesised mechanism for pterygium formation is that ultraviolet light from the temporal side results in the transcameral focusing and concentrating of light on the nasal limbus causing oxidative stress 9.…”