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Abstract

We would like to thank Takkar and associates for showing interest in our research, as well as for their comments. As they have mentioned, axial length (AL) measurements using partial coherence laser interferometry (PCLI) may be inaccurate, especially in patients with macula-off retinal detachment (RD). 1 Abou-Shousha M. Helaly H.A. Osman I.M. The accuracy of axial length measurements in cases of macula-off retinal detachment. Can J Ophthalmol. 2016; 51: 108-112 Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar Therefore, we agree that it may be better to use A-scan ultrasonography as a preoperative examination, especially for patients with macula-off RD. In this study, both PCLI and A-scan ultrasonography were used as preoperative examinations to compare AL changes. However, only PCLI was used in postoperative examination. Contrary to their assertion, as shown in our findings, the mean preoperative AL confirmed by PCLI was not significantly different between the operated eye and the fellow eye (P = .554). Moreover, the mean preoperative AL measured with A-scan was not significantly different between the operated eye and the fellow eye (P = .607). More importantly, preoperative AL was not used as a reference time point for comparison after 6 months. Instead of preoperative AL, AL measured 6 months postoperatively was used as a reference point for comparison of changes in AL. This is because it is assumed that the initial effect of scleral encircling on axial length is the greatest, and the effect then diminishes over time. Nevertheless, as Takkar and associates have pointed out, when planning and implementing a prospective study it may be desirable to follow up with A-scan ultrasonography to achieve more precision, particularly in patients with macula-off RD. Despite some drawbacks inherent in PCLI-measured AL, use of PCLI has some advantages when compared to A-scan. In macula-on RD, not macula-off RD, AL can be measured correctly based on the assumption that the patient's compliance to fixation is normal. In a recently published study, performing pars plana vitrectomy or pneumatic retinopexy in patients with macula-on RD resulted in no change in AL before vs after surgery. This finding was confirmed using both PCLI and A-scan ultrasonography. 2 Pongsachareonnont P. Tangjanyatam S. Accuracy of axial length measurements obtained by optical biometry and acoustic biometry in rhegmatogenous retinal detachment: a prospective study. Clin Ophthalmol. 2018; 12: 973-980 Crossref PubMed Scopus (10) Google Scholar This suggests that in patients with macula-on RD, there is no difference in AL as measured by PCLI or A-scan ultrasonography. In addition, it is known that AL measured using PCLI is feasible in highly myopic patients and can lead to satisfying results and good signal quality. 3 Roessler G.F. Talab Y.D. Dietlein T.S. et al. partial coherence laser interferometry in highly myopic versus emmetropic eyes. J Ophthalmic Vis Res. 2014; 9: 169-173 PubMed Google Scholar It is also known that visual axis as measured using PCLI reflects AL more accurately than optical axis measured using A-scan ultrasonography when posterior staphyloma is present in patients with high myopia. 4 Lege B.A. Haigis W. Laser interference biometry versus ultrasound biometry in certain clinical conditions. Graefes Arch Clin Exp Ophthalmol. 2004; 242: 8-12 Crossref PubMed Scopus (71) Google Scholar In our study, there were 10 patients with high myopia, who accounted for 26.3% of all patients, which is higher than usual prevalence. In a demographic study of Koreans, the prevalence of high myopia was 5.0%. 5 Rim T.H. Kim S.H. Lim K.H. Choi M. Kim H.Y. Baek S.H. Refractive errors in Koreans: The Korea National Health and Nutrition Examination Survey 2008-2012. Korean J Ophthalmol. 2016; 30: 214-224 Crossref PubMed Scopus (53) Google Scholar Therefore, we speculate that postoperative AL as measured using PCLI is more accurate than AL measured using A-scan ultrasonography in patients with high myopia. Long-term Effect of Scleral Encircling on Axial ElongationAmerican Journal of OphthalmologyVol. 193PreviewWe read with interest the study “Long-term Effect of Scleral Encircling on Axial Elongation” by Lee and associates.1 Following a retrospective analysis of myopic patients undergoing surgery for retinal detachment (RD), the authors concluded that encircling the sclera may accelerate progression of myopia by significantly increasing axial length (AL). The change in AL was nearly 8 times higher as compared to fellow eyes in the short term, and nearly 10 times higher in the long term. Full-Text PDF