Prevalence of Glaucoma in Patients With Vitiligo
Vitiligo is an acquired idiopathic disease characterized by depigmented maculae and melanocytic destruction. We determined the prevalence of glaucoma in 49 patients who had presented to the dermatology polyclinic with vitiligo and compared that with the prevalence of glaucoma in 20 age- and sex-matched healthy controls. All patients were given an ophthalmologic examination to identify any glaucomatous changes. In the vitiligo group, 9 patients (18.4%) were found to have signs of normal-tension glaucoma (NTG), while there were no signs of NTG in the control group. This difference between the 2 groups was statistically significant (P=.04). Because glaucoma can cause permanent vision loss when left untreated, its greater prevalence among patients with vitiligo suggests that these patients should be carefully monitored.
Practice Points
- Patients with vitiligo may exhibit pigmentary abnormalities of the iris and retina.
- Normal-tension glaucoma may develop in patients with vitiligo.
- Glaucoma progresses slowly and may lead to vision loss; as a result, dermatologists should be alert to the presence of glaucoma in vitiligo patients.
Although there are various studies exploring ocular symptoms in patients with vitiligo,9-15 only 1 study has examined the incidence of glaucoma in this group of patients.5 Biswas et al11 examined ocular signs in 100 patients with vitiligo and found that 23% of patients had hypopigmented foci in the iris, 18% had pigmentation in the anterior chamber, 11% had chorioretinal degeneration, 9% had hypopigmentation of the retinal pigment epithelium, 5% had uveitis, and 34% were evaluated as normal. In this study, the authors concluded that there was a strong relationship between vitiligo and eye diseases.11 When Gopal et al9 compared the eye examinations of 150 vitiligo patients and 100 healthy controls, they found uveitis, iris, and retinal pigmentary abnormalities in 16% of the vitiligo patients (P<.001).
Rogosić et al5 examined the incidence of glaucoma in 42 patients with vitiligo and found primary open-angle glaucoma in 24 (57%) patients. The patients had a mean age of 56 years, mean disease duration of 13 years, and mean IOP of 18 mm Hg for the right eye and 17.5 mm Hg for the left eye. The incidence of glaucoma was significantly higher in patients with vitiligo (P<.001) and increased with disease duration.5
Similar studies, however, have failed to show a relationship between vitiligo and glaucoma. In a study that evaluated the retinal pigment epithelium and the optic nerve in patients with vitiligo, Perossini et al10 found that the fundus examination of the patients was perfectly normal.
In our study, we detected NTG in 18.4% of patients with vitiligo. We did not find a significant statistical difference between patients with and without glaucoma (Table 2). Rogosić et al5 found a significant relationship between age and glaucoma incidence, but we did not find such a relationship, which we believe is because the mean age of our patients was lower than the prior study.
In vitiligo, melanocytes are destroyed through an unknown mechanism. Although the cellular and molecular mechanisms causing melanocytic destruction have not yet been determined, various hypotheses have been put forward to explain the etiopathogenesis of vitiligo. Among these, the most commonly held hypotheses are the neural, self-destruction, and autoimmune hypotheses.16
Based on the observation that stress and serious trauma could precipitate or trigger the onset of vitiligo,16 the neural hypothesis holds that neurochemical mediators released from the edges of the nerve endings exert toxic effects on melanocytes. The fact that both melanocytes and choroidal pigment cells originate from the mesenchyme and dermatomal spreading of segmental vitiligo are arguments propounded in favor of this hypothesis.17
The self-destruction hypothesis suggests that the intrinsic protective mechanisms that normally enable melanocytes to eliminate toxic intermediate products or metabolites on the melanogenesis path have been impaired in patients with vitiligo.18,19 There is evidence of increased oxidative stress over the whole epidermis of patients with vitiligo.20 Thus, free radicals affect melanin and cause membrane damage via lipid peroxidation reactions.21
The autoimmune hypothesis proposes a clinical relationship between vitiligo and several diseases believed to be autoimmune. Because the macrophage infiltration observed in vitiligo lesions is more pronounced on the perilesional skin, this hypothesis holds that macrophages may play a role in melanocyte removal.21 The Koebner phenomenon observed in vitiligo lends support to the critical role of trauma in the etiopathogenesis of the disease.
Although we could not explain the co-presence of vitiligo and glaucoma, we believe that it may result from the fact that both diseases are observed in tissues that have the same embryologic origin and etiology, perhaps vascular or neural disorders, excessive accumulation of free radicals, or the triggering of apoptosis. Dermatologists should be alert to the presence of glaucoma in patients with vitiligo because glaucoma is an eye disease that progresses slowly and may lead to vision loss.
