Comment on: Corneal collagen cross-linking with riboflavin and ultraviolet: A light for keratoconus

I thank Parthasarathy[1] for the specific interest in our work[2] on corneal collagen cross-linking with riboflavin. This study was a part of a larger study on various aspects of keratoconus at our center. Thus, vernal keratoconjunctivitis was not specifically mentioned in this article. In another original paper submitted for publication, we have reported that 24.4% of patients with keratoconus had symptomatic ocular allergies.

I thank Parthasarathy [1] for the specific interest in our work [2] on corneal collagen cross-linking with riboflavin. This study was a part of a larger study on various aspects of keratoconus at our center. Thus, vernal keratoconjunctivitis was not specifically mentioned in this article. In another original paper submitted for publication, we have reported that 24.4% of patients with keratoconus had symptomatic ocular allergies.
The seven eyes did not qualify for inclusion in the stable or improved category as the criteria mentioned was ±0.5 DS. If the criterion was changed to ±1.5 D, all eyes remained stable in our study. Thus, no patient lost best corrected visual acuity (BCVA). Change in refraction after treatment is a common finding in our patients (unpublished data). Of the seven eyes in question, only two had co-existing allergic eye disease.
Postoperative ultrasonic pachymetry has been performed for each patient at each follow-up visit. The change pattern was not significant, as seen from the Table 1 of the published article. [1] About the values showing a large standard deviation, it is due to the changes in keratometry in various patients. If we look individually, we have had patients showing responses varying from up to a 7 D change in astigmatism to no change. Thus the large standard deviations in the statistical analysis. The BCVA did not drop in our series, as mentioned earlier.
The issue of corneal wavefront evaluations is the subject of another ongoing study at our center.

Comment on: Corneal collagen cross-linking with riboflavin and ultraviolet: A light for keratoconus
Dear Editor, I read with interest the article by Agrawal on the results of "Corneal collagen cross-linking with riboflavin and ultraviolet -a light for keratoconus: results in Indian eyes". [1] The author has done commendable work and the results do definitely add to the present body of evidence. However, I seek clarifications from the author.
Was the presence of vernal keratoconjunctivitis (VKC) specifically looked for as we know that there is an association between VKC and keratoconus? [2][3][4] The author mentions in the results section that the best corrected visual acuity (BCVA) improved or remained stable in 54% (20/37) and 28% (10/37) respectively of the eyes. Would the authors state what the result in the remaining seven eyes was? Did the patients have loss of BCVA, and if so, why? Did these patients have VKC?
In addition to the Orbscan, postoperative ultrasound pachymetry and topography should also have been performed to assess the change in the corneal thickness. This would be better than an Orbscan in assessing the change of K values. This is important since any scanning slit-based imaging technology would be affected by the stromal haze that appears after collagen cross-linking in these patients.
In the results section of the article, Table 1 shows values and change of Kmax Apex, Kmax (D), astigmatism (D) and visual acuity with large standard deviations. This could indicate variability in the response of the procedure, increase in the keratometric values in astigmatism and drop in visual acuity in some patients. The K-values decreased in 66% (24/37) of the eyes and were stable in 22% (8/37) of the eyes; five of the patients had an increase in keratometry. The author would do well to allude to it further.
The details of the wavefront analysis should have been elaborated further unless it is a subject of another study. Studies performed at our centers indicated that wavefront analysis can be used as an additional tool to detect forme fruste in keratoconus patients if the wavefront decomposition is performed up to the 4th order. I would encourage the author to share information if he has details regarding the same.