Ophthalmic Aspects of Erectile Dysfunction Drugs

is still unknown why PDE-5 inhibitors cause nonarteritic anterior ischemic optic neuropathy in some patients, even though these drugs improve endothelial function. In our two recent prospective clinical studies in cooperation between the ophthalmology and urology departments of Harran University Medical School, we have studied the acute and chronic effects of sildenafil on tear and ocular functions.5,6 In the study about sildenafil on tear functions, the cotton thread and Schirmer I tests were performed, and tear breakup time was determined in all subjects just before and 1 hour after receiving oral sildenafil 50 mg. The results before and after the medication for each test were statistically insignificant. The evaluation of the acute effects on tear functions at the peak drug serum levels was important because ED and abnormal tear functions are generally seen in an older population. Conversely, in our other study about the long-term effects of the same drug on ocular functions, we found that there was no clinically or statistically significant difference in visual acuity, color discrimination, intraocular pressure, mean deviation, results of the cotton thread and Schirmer I tests, tear breakup time, or amplitude and implicit time of b-wave and wavelet index in chronic users who had received therapy for 3 months one or more times a week (average two to three tablets). Like Lee and Newman,1 we think that more prospective studies are needed to determine the ocular effects of PDE-5 inhibitors—the sheer number of prescriptions for various indications, as well as the variations of the molecules of PDE-5, make more studies imperative.

as a quotient, it would not be able to elicit vascular changes if the degree of change in the arterioles corresponded to an equal degree of change in venules. However, we also agree with their comment that the AVR continues to be an important measure of the effect of systemic disease on the microcirculation. The original motivation for developing the concept of an AVR was to provide a measure of vascular caliber that was dimensionless and devoid of any potential magnification effect from retinal photography that might make comparisons between individuals susceptible to error. If future studies are going to rely on measures such as the central retinal arterial equivalent and central retinal vein equivalent, then it must be borne in mind that these measures are not dimensionless, and caution must be taken in comparing these measurements between individuals. NIALL PATTON, MRCOPHTH TARIQ ASLAM, DM BALJEAN DHILLON, FRCOPHTH

Edinburgh and Manchester, United Kingdom

REFERENCE

1. Patton N, Maini R, MacGillivray T, Aslam TM, Deary IJ, Dhillon B. Effect of axial length on retinal vascular network geometry. Am J Ophthalmol 2005;140:648 – 653.

Ophthalmic Aspects of Erectile Dysfunction Drugs

AYHAN VERIT, MD HALIT OGUZ, MD

EDITOR:

Sanliurfa, Turkey

WE READ THE REVIEW ARTICLES OF LEE AND NEWMAN1 AND

of Fraunfelder.2 The authors documented the ophthalmic complications such as transient changes in color vision, blue tingle to vision, increased sensitivity to light, conjunctival hyperemia, ocular pain, photophobia, and especially nonarteritic anterior ischemic optic neuropathy of all three (sildenafil, vardenafil, and tadalafil) phosphodiesterase (PDE)-5 inhibitors used to treat erectile dysfunction (ED). Because vardenafil and tadalafil are relatively new drugs, fewer reports have been published about them than about sildenafil, an agent that has been prescribed since 1998. In addition, a new PDE-5 molecule, DA-8159, will be in the market soon.3 We think that in the future, patients receiving PDE-5 inhibitors— currently drugs of on-demand use—will possibly switch to prophylactic drugs to treat either ED or to improve endothelial function. The latter may be particularly important in patients with cardiovascular problems, diabetes, pulmonary hypertension and inflammation, and even depression.3,4 Thus all clinicians, including ophthalmologists, will surely soon be more aware of this group of drugs and their complications than is currently the case. It 598

AMERICAN JOURNAL

REFERENCES

1. Lee AG, Newman NJ. Erectile dysfunction drugs and nonarteritic anterior ischemic optic neuropathy. Am J Ophthalmol 2005;140:707–708. 2. Fraunfelder FW. Visual side effects with erectile dysfunction agents. Am J Ophthalmol 2005;140:723–724. 3. Ahn GJ, Yu JY, Choi SM, et al. Chronic administration of phosphodiesterase 5 inhibitor improves erectile and endothelial function in a rat model of diabetes. Int J Androl 2005;28: 260 –266. 4. Frajese GV, Pozzi F. New achievement and novel therapeutic applications of PDE5 inhibitors in older males. J Endocrinol Invest 2005;28:45–50. 5. Oguz H, Verit A, Ozkul Y, Gurkan T, Ciftci H. No effects of sildenafil treatment on ocular functions. Ann Ophthalmol 2005;37:85–90. 6. Oguz H, Verit A, Gurkan T, Yeni E. The acute effects of sildenafil on tear functions. Ann Ophthalmol 2005; 37(4):281–284. OF

OPHTHALMOLOGY

MARCH 2006