The incidence of keratoconus and its association with ocular disorders in Lahore population

This study was conducted to check predominance of keratoconus in male and female of the various age groups in Pakistan and to check the severity of disease in keratoconus patients. Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a conelike shape. A cross-sectional, analytical study was performed between September 2016 to May 2017 on Keratoconus patients visiting Layton Rahmatullah Benevolent Trust Hospital and Sir Ganga Ram Hospital during their ophthalmic consultation. The techniques used for the diagnosis of Keratoconus were Visual Acuity by Snellen chart, Ophthalmoscopy, Orbscan corneal topography, and Slit lamp bio microscopy. Total 110 patients of Keratoconus were studied in which 62 were females and 48 were males. Patients developed both unilateral as well as bilateral conditions. Visual acuity from normal to high vision loss was also observed in Keratoconus patients. Different disorders with different percentage such as Munson’s sign were present in 68 patients, Rizutti’s sign was present in 30 patients, Vogt’s striae were present in 26 patients and Fleischer ring was present in 23 patients. 19 patients had Atopic syndrome and 6 patients had Leber’s Congenital Amaurosis were also associated with keratoconus.


Introduction
Keratoconus is a chronic, progressive, noninflammatory disease of the cornea.It is a common primary ectasia of the cornea characterized by thinning and distortion of the cornea which results in the protrusion of the cornea and it assumes a conical shape.It usually affects all layers of the cornea.It develops in puberty and progresses until the third or fourth decade of life.So in the progressive stage, visual acuity lost which cannot be correct with spectacles.Keratoconus affects both genders and all ethnicities [1, 2].The early forms of keratoconus go unnoticed unless corneal topography is performed but the severity of the disorder at the time when the progression stops can range from very mild irregular astigmatism to severe thinning, protrusion, and scarring which cause severe visual impairment that requires keratoplasty [3].The most prominent early features of keratoconus are the thining of the corneal stroma, breaks in the Bowman layer and the formation of a Fleischer ring that is, an iron deposit in the basal epithelial cells.Vogt's striae; folds or fine vertical striations in the Descemet's membrane due to compression, Munson sign; in downward position V-shape malformation of the lower eyelid due to corneal protrusion, Rizutti's sign; a bright conical reflection on nasal cornea when light is directed from the temporal side, acute Variables that were selected for further analysis and assessment are Age, Gender, Unilateral or Bilateral keratoconus, Munson sign, K-readings, Rizutti's sign, Vogt's striae, Fleischer ring, Syndrome (if any).For clinical evaluation of the patients of Keratoconus following methods are adopted Visual acuity, Direct and indirect Ophthalmoscopy, Corneal topography, Slit lamp biomicroscopy.Chi-Square Test was performed and a comparison between different age groups and the number of patients of keratoconus was done, the significant level was 0.000.Unilateral keratoconus, bilateral keratoconus, visual disability, history of eye rubbing and Munson's sign showed a significant level of 0.000.Rizzuti's sign was observed at a significant level of 0.002, Vogt's striae were observed at a significant level of 0.003.The significant level was P ≤ 0.05.Fleischer ring showed a significant level of 0.529 and different k-readings of patients of keratoconus showed a significant level of 0.095.
Keratoconus is a progressive, noninflammatory disease of the cornea which is characterized by progressive thinning and protrusion of the cornea, which eventually leads to mild or markedly impaired vision due to high myopia and irregular astigmatism In this study, we determined the predominance of Keratoconus in Pakistan.110 cases of Keratoconus have observed in which the most representative age group was 16-30, so it is a problem for young people.Keratoconus usually affects both genders in some cases male dominates females [10].While in others females are more affected [11].In our study, the disease is more prevalent in females.The disease is initially occurring as unilateral but on progression, it becomes bilateral and asymmetrical.The prevalence of unilateral range from 14.3% to 41% when detected by keratometry alone [12] while with computerized topography, unilateral Keratoconus has 0.5% to 4% [13].Bilateral Keratoconus is more common in patients, as in our study the cases of bilateral Keratoconus is high.

Figure 2. The predominance of visual disability in 110 patients of keratoconus
In our study, 61 patients of Keratoconus gave a positive history of eye rubbing.An association between eye rubbing and Keratoconus has long been described.It is considered a major risk factor.Before the development of Keratoconus, the majority of the patients have a history of habitual eye rubbing.Many reports show that about half of Keratoconus patients rub their eyes [14].So, it is clear that there is a strong link between the eye rubbing and development of Keratoconus, and has certain differences linked to the eye rubbing is gentle or vigorous.Variation in usual length of rubbing is also notable e.g.Keratoconus patients have more duration of eye rubbing ranging from 10-seconds to 180-seconds than the characteristically less than the 15-seconds duration of rubbing in allergic or infective ocular disorders, in addition, less than 5seconds among people without any eye condition [15].In this study, 19.1% of patients showed a family history of Keratoconus while the other studies established that furthermost percentages of general family history were usually lower than 20%.Family history for Keratoconus is due to from either environmental or genetic agents.However, it not always obvious which of the two is most significant in the pathogenesis of the disease until drawing family pedigree [16].In our study, Munson's sign was present in 68 patients and also Rizutti's sign was present in 30 patients which occur disease progresses.A Munson's sign, a V-shaped deformation of the lower lid, as well as a bright reflection of the nasal area of the limbus called Rizzuti's sign [17].We also observed 26 patients who had Vogt's striae and 23 patients had a Fleischer ring.Some of the early biomicroscopic signs were; Fleischer's ring (iron deposition in partial or complete circular form in the epithelium closed to the base of the cornea and Vogt's striae (fine vertical lines produced by compression of Descemet's membrane).Corneal topography was performed which showed that 29 patients of Keratoconus had mild<45D k-readings, 47 patients of Keratoconus had moderate 45>52D kreadings and 34 patients of Keratoconus had severe>62D k-readings.Topography alone cannot lead to a direct diagnosis of Keratoconus, as it must collaborate with clinical signs, symptoms, and thickness optical coherence tomography scans.These diagnostic tools help to differentially distinguish and diagnose Keratoconus from cases of normal irregular astigmatism and corneal dystrophies [18].Keratoconus

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. Keratoconus affects typically at puberty and young adults until the third or fourth decade of life with the age between approximately 14 and 35 years, during which the disease can progress or spontaneously arrest.The causes of Keratoconus are multifactorial and are still not completely understood.There are proofs that biochemical, biophysical, and genetic factors play a major contribution in the etiology of this ecstatic corneal disorder.The interplay between environmental and genetic factors is convincing for the development of the disease [9].

disease [6]. In a study performed in the Midlands area of the
may associate with ocular diseases, in our study, we found 19 patients having the atopic syndrome and 6 patients having Leber's Congenital Amaurosis associated with Keratoconus.It has been reported that approximately 35% of patients with Leber Keratoconus is a disease of the cornea in which cornea thins and protrudes, resulting in visual impairment.The disease is much prevalent in Asian population.It usually affects both genders and all ethnic groups.But a higher percentage is observed in females.Both genetic and environmental factors are involved.Keratoconus may associates with ocular disorders like Leber's congenital amaurosis etc and Atopic syndrome as a risk factor.