Keratoconus Associated with Continual Eye Rubbing Due to Punctal Agenesis
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Cornea 19(4): 567–569, 2000. © 2000 Lippincott Williams & Wilkins, Inc., Philadelphia Keratoconus Associated with Continual Eye Rubbing due to Punctal Agenesis Richard G. Lindsay, B.Sc.Optom., M.B.A., F.A.A.O., Dip.C.L., Adrian S. Bruce, B.Sc.Optom., Ph.D., F.A.A.O., and Ian F. Gutteridge, M.Sc.Optom., F.A.A.O. Purpose. To highlight a possible causal effect of eye rubbing in in this condition associated with blepharitis.1 However, a causal the etiology of keratoconus. Methods. A 43-year-old man pre- relationship between eye rubbing and keratoconus has been diffi- sented to the practice of one of the authors (I.F.G.) with the com- cult to prove.5 If a case of unilateral keratoconus was shown to plaint of gradual onset reading difficulty. History revealed the have developed where there had been a history of digital rubbing patient to have experienced constant epiphora in the right eye solely confined to the affected eye, it would lend support to the throughout his life as a result of punctal agenesis, which necessi- theory that mechanical trauma is a major etiologic factor in the tated frequent wiping of this eye. Vision in the patient’s right eye had been reduced for approximately 20 years. Results. Based on development of keratoconus. ocular examination, the patient was diagnosed as having unilateral A case of unilateral keratoconus is presented where there is a keratoconus in the right eye. Conclusion. It is thought by some confirmed history of eye rubbing and wiping as a result of punctal that keratoconus is associated with, or indeed caused by, persistent agenesis in the ipsilateral eye. The contralateral eye, without rubbing of the anterior eye. While a number of studies support a symptoms of epiphora or a history of eye rubbing, was devoid of genetic basis for keratoconus in some patients, it is possible that any evidence of keratoconus. mechanical factors play a role in the development of this condition in other patients. This paper presents a case of unilateral kerato- conus, where there is a confirmed history of habitual eye rubbing CASE REPORT and wiping of excess tears as a result of punctal agenesis in the ipsilateral eye, thereby suggesting a possible causal relationship of A 43-year-old man presented to the practice of one of the au- eye rubbing in the etiology of keratoconus. thors (I.F.G.) with the complaint of gradual onset reading diffi- Key Words: Keratoconus—Eye rubbing—Mechanical trauma— culty. He had been told that he had been born without lacrimal Punctal agenesis. puncta in the right eye. Surgery was recommended at age 18 months; however, the patient’s parents decided not to proceed at this time as they had been advised that “there was a significant risk of permanent scarring” with this option. Consequently, the patient Keratoconus is a progressive disorder, with an onset anywhere had experienced constant epiphora in the right eye throughout his between 8 and 40 years of age, in which the cornea assumes a life that necessitated frequent wiping of this eye. The patient es- conical shape as a result of noninflammatory thinning of the cor- timated that his right eye was wiped with a handkerchief about 50 neal stroma. It is usually a bilateral disease but is often asymmet- times a day due to this congenital absence of the puncta. He ric. True unilateral keratoconus is rare; although, only one eye may described that, in addition to wiping the eye, he used a rubbing be affected initially.1,2 The real incidence of unilateral keratoco- action involving a pushing into the globe prior to wiping from the nus has certainly undergone a significant downward revision over inner canthus in a temporal direction. The left eye was normal, as the last few years3,4 with the introduction of computer-assisted far as the patient was concerned, with no epiphora and with no videokeratoscopy enabling the detection of keratoconus in fellow history of excessive or unusual eye rubbing. eyes that otherwise appear relatively normal on ocular examination. The patient believed that the vision in his right eye had been It is thought by some that keratoconus is associated with, or below normal for approximately the last 20 years. He recalled that indeed caused by, persistent rubbing of the anterior eye.1 For ex- all visual examinations during childhood (up to age 17) had ap- ample, the frequent occurrence of keratoconus in Down’s syn- parently revealed normal visual acuities in both eyes. Decreased drome is sometimes attributed to the high incidence of eye rubbing visual acuity in the right eye was then first noticed at a vision screening performed when the patient was 23 years old. Submitted August 2, 1999. Revision received November 11, 1999. Ac- Thorough questioning revealed no other ocular problems, pres- cepted November 23, 1999. ent or past. There was no significant familial ocular history. The From the Department of Optometry and Vision Sciences (R.G.L., patient’s general health was excellent, with no current allergy or A.S.B., I.F.G.), University of Melbourne, and the Victorian College of atopy, although he did advise that he had suffered from asthma Optometry (A.S.B.), Australia. Address correspondence and reprint requests to Dr. Richard G. between the ages of 6 and 15. He was not using any medication on Lindsay, 376 Albert Street, 6th Floor, East Melbourne VIC 3002, a regular basis. Australia. Unaided vision of 6/30 OD, 6/6++ OS was improved to 6/7.5 567 568 R.G. LINDSAY ET AL. OD, 6/4.8 OS with a manifest refraction of +1.50/−3.75 × 85 OD, −0.25 diopter sphere (DS) OS. Pinhole in the right eye further improved acuity to 6/6 OD. A scissors reflex was obtained with retinoscopy in the right eye while the left retinoscopic reflex was normal. A +1.00 D addition gave N4 near acuity. The explanation for the patient’s presenting complaint was early presbyopia for which reading spectacles were prescribed. Slit-lamp examination showed an absence of the superior and inferior punctum lacrimale in the right eye. In the left eye, only the superior punctum lacrimale was present. This is illustrated dia- grammatically in Figure 1. It was not possible to determine wheth- er the patient lacked canaliculi as well as lacrimal puncta in the right eye. Very slight corneal thinning was noted in the right eye, about 1 mm inferior to the visual axis, while the left cornea was normal. There were no signs of any corneal opacification or striae FIG. 2. Topographic map of the patient’s right cornea. Note the in- in either eye. ferior steepening typical of keratoconus. Videokeratoscopy with the TMS-2 (Computed Anatomy Inc., New York, NY, U.S.A.) gave a topographic map indicative of Eye rubbing has been implicated in the pathogenesis of kerato- early keratoconus in the right eye (Fig. 2) with distinctive asym- conus. Indeed, it has been postulated that the usual inferior loca- metric pattern and localized inferior steepening. The topographic tion of the cone in keratoconus is due to the presence of the most map of the left cornea revealed a small degree of with-the-rule senile epithelial cells in this location, with these cells possibly astigmatism without suggestion of keratoconus (Fig. 3). more vulnerable than the younger epithelial cells to the subtle All other aspects of the ocular examination were unremarkable. trauma of eye rubbing and, therefore, possibly more prone to re- Based on these findings, a diagnosis of unilateral keratoconus in leasing enzymes that thin the cornea.9 A high association of eye the right eye was made. The patient was well adapted to the poor rubbing with keratoconus has been reported in the literature, al- vision in the right eye, so spectacle or contact lens correction of though, as was stated earlier, a cause-and-effect relationship is this eye was not considered necessary. difficult to prove.5 Coyle10 reported the case of a boy who was born with an atrial DISCUSSION ventricular septal defect and who underwent open heart surgery at the age of two years. The operation was successful; however, he The case presented in this paper is interesting in that it involves subsequently developed paroxysmal atrial tachycardia. At the age a relatively rare clinical entity—unilateral keratoconus—where the of five years, the boy discovered that the tachycardia could be unilateral nature of the condition could be explained by a history stopped by vigorously massaging his left eye (presumably due to of unilateral mechanical trauma (eye rubbing) due to punctal agen- stimulation of the oculocardiac reflex). Ocular examination at age esis in the same eye. seven years revealed no abnormalities and visual acuities of 6/6 in Tears are lost from the eye by lacrimal drainage and evapora- both eyes. When he was 11 years old, the boy was found to have tion. Epiphora may result from lacrimal drainage obstruction, ne- keratoconus in his left eye with best corrected acuity of only 6/18. cessitating wiping or rubbing of the eye. Evaporation of the tears There was no sign of keratoconus in the right eye, with visual is a continual feature of the open eye, and is controlled by both the acuity in this eye still 6/6. superficial lipid layer of the precorneal tear film and the mecha- Gritz and McDonnell11 reported the case of a man who devel- nism and rate of blinking.6 The lipid layer inhibits evaporation, oped keratoconus in his right eye over a period of less than a year, especially in conditions of low humidity and turbulent tear flow.7 apparently as a result of pressing vigorously with his fist against Interestingly, this patient experienced no symptoms of epiphora in the left eye, which lacked the inferior punctum.