Anders Gyldenkerne

To describe the relationship between the axial length of the eye and age, and report reference values for axial length in a general adult European population. As part of the epidemiological study FORSYN, the axial length in both eyes of a population-representative sample of 3,364 adult citizens (48.8% men, 51.2% women) was measured using swept-source optical coherence tomography. Approximately one third of the sample accepted the invitation (3,384 out of 9,708, 32.7%), and after correction for selection bias, multiple linear regression was used to estimate how the axial length depended on age in the whole population and among men and women. Based on the findings, reference values for the axial length in the adult population were calculated. Logistic regression was performed to examine whether the prevalence of axial lengths longer than or equal to 26.0 mm differed with age in both men and women. The axial length showed no significant correlation with age (multiple linear regression, slope -0.002, 95% CI -0.005 to 0.0001, p = 0.06), but was significantly (unpaired t-test, p < 0.0001) longer in men (23.99 mm) than in women (23.53 mm). The axial length was longer than or equal to 26.0 mm in 3.8% (95% CI 3.4 to 4.2) of the adult population. There was no significant difference in age among participants with axial length above and below this value (logistic regression, OR = 1.00, p = 0.42). Global reports of increased axial length in the younger demographic does not seem to apply to the general Danish population. When evaluating axial length, it should be considered that reference values differ among men and women.

Purpose To examine whether the amplitude of accommodation, the accommodative response, and the accommodative facility is affected and correlated with changes in higher-order aberrations for patients with high myopia surgically treated with small-incision lenticule extraction (SMILE). Methods 35 highly myopic eyes (myopic spherical equivalent of at least 6 diopters) of 35 patients treated with SMILE were included. Assessments were made before and 3 months after surgery. Donders push-up-method was used to measure the amplitude of accommodation. The accommodative response was assessed using an open-field autorefractor"Grand Seiko WAM-5500" (Grand Seiko Co. Ltd., Hiroshima, Japan) in combination with a Badal optometer and stimuli of accommodation at 0.0, 0.5, 1.25, 2.0, 3.0, and 4.0 D, respectively. Accommodative facility was measured at 40 cm with +/- 2,00D flipper lenses. All measurements of accommodation were performed monocularly with the refractive error corrected with soft contact lenses. Results The amplitude of accommodation did not change statistically significantly (mean difference -0.24 D (SD 0.98), 95% CI of mean difference -0.58 D to 0.11 D, paired-sample t(34) = -1.39; P = 0.17). The accommodative responses at 0.0, 0.5, 1.25, 2.0, 3.0, and 4.0 D did not statistically significantly change either (F(6,29) = 1.15; P = .36). Finally, the accommodative facility was also unchanged with a mean difference of 1.11 cycles per minute (SD 5.11, 95% CI of mean difference -0.64 to 2.87, paired-sample t(34) = 1.29; P = 0.21). No clinically significant associations between changes in accommodation and higher-order aberrations were found. Conclusions SMILE does not alter the amplitude of accommodation, the accommodative response, nor the accommodative facility for highly myopic patients, and the surgically induced corneal higher-order aberrations do not affect the accommodative function.

Purpose: To assess the influence of small-incision lenticule extraction (SMILE) for high myopia on the visual image quality assessed by the logarithm of the visual Strehl ratio (logVSX) and put this into a clinical context by pairwise comparing the logVSX of postoperative eyes with those of myopic controls wearing spectacles and/or contact lenses. Setting: University hospital. Design: Prospective and cross-sectional clinical study. Methods: Patients with a myopic spherical equivalent of at least 6.00 diopters treated with SMILE aimed at emmetropia and correspondingly myopic controls corrected with spectacles and/or contact lenses were included. The logVSX calculation was divided into habitual logVSX based on the wavefront aberration measurement directly and optimal logVSX calculated in a theoretical through-focus experiment to obtain the best-achievable logVSX. Results: A total of 117 eyes of 61 patients and 64 eyes of 34 myopic controls were included. SMILE did not affect the habitual logVSX but worsened the optimal logVSX (P < .001). The postoperative habitual logVSX was statistically significantly worse compared with contact lenses (P = .002). The postoperative optimal logVSX was significantly worse compared with both spectacles (P < .01) and contact lenses (P = .003). There was no statistically significant difference in habitual or optimal logVSX between spectacles and contact lenses. Conclusions: SMILE for high myopia does not affect the habitual logVSX but decreases the optimal logVSX slightly. The postoperative habitual logVSX is worse than for contact lenses but not spectacles, and the postoperative optimal logVSX is worse than for both contact lenses and spectacles. There is no statistically significant difference in either habitual or optimal logVSX between spectacles and contact lenses.

Purpose: To assess whether small-incision lenticule extraction (SMILE) for high myopia reduces the binocular visual function assessed by stereoacuity, binocular visual acuity, binocular contrast sensitivity, and binocular summation. Setting: University hospital. Design: Prospective case series. Methods: Patients with a myopic spherical equivalent of at least 6.00 diopters (D) scheduled for SMILE aimed at emmetropia were included. Psychophysical testing was performed with correction preoperatively but no correction postoperatively. Stereoacuity was assessed with the Randot Circles test and the near Frisby test, visual acuity (monocular and binocular) was assessed with high-contrast Early Treatment Diabetic Retinopathy Study charts, and contrast sensitivity (monocular and binocular) was assessed with the Pelli-Robson chart and the Freiburg Acuity and Contrast Test. Binocular summation was calculated by comparing the binocular score against the best monocular score. Results: A total of 138 eyes of 69 patients were included. The mean spherical equivalent changed from −7.46 D ± 1.06 (SD) to −0.23 D ± 0.40 postoperatively. Stereoacuity did not change significantly postoperatively; median change (interquartile range) was −0.32 (−6.21 to 1.55) seconds of arc with the Frisby test and 0.00 (−7.5 to 5.0) seconds of arc with the Randot test (P ≥ .06). Binocular postoperative uncorrected distance visual acuity was not different from the preoperative corrected distance visual acuity (P = .40). Contrast sensitivity declined slightly monocularly with both tests of contrast sensitivity but was unaltered binocularly (P ≥ .08). Binocular summation for visual acuity and contrast sensitivity was unaltered following surgery (P ≥ .09). Conclusions: SMILE for high myopia did not reduce the binocular function assessed by stereoacuity, binocular visual acuity, binocular contrast sensitivity, and binocular summation.

Purpose: To investigate if postoperative induced refractive astigmatism following small-incision lenticule extraction (SMILE) could be predicted by preoperative objective astigmatism measured with autorefraction, keratometry, and Scheimpflug tomography. Setting: University Eye Clinic Design: Retrospective case series Methods: Only eyes without preoperative subjective astigmatism treated with SMILE for myopia were included. Postoperative subjective astigmatism was compared with preoperative objective astigmatism. Examinations were performed before and 3 months after surgery and included subjective refraction, keratometry, autorefraction, and Pentacam HR measurements. Astigmatism was analyzed using double-angle plots and multivariate statistics. Results: 358 eyes of 358 patients were included. Mean preoperative sphere was -7.33 D ± 1.46 (SD). Postoperative spherical equivalent (SE) was -0.30 D ± 0.49. After surgery, 79.6% and 98.9% of patients had a subjective cylinder ≤ 0.50 D and ≤ 1.00 D, respectively. Preoperative objective astigmatism measured with keratometry, autorefraction, and Scheimpflug tomography was significantly different (p<0.05) from postoperative subjective refraction when all patients were analyzed; for patients with postoperative refractive astigmatism ≥ 0.50 D, preoperative astigmatism with keratometry and Scheimpflug tomography was not significantly different from the postoperative refractive astigmatism. A preoperative objective astigmatism ≥ 0.50 D increased the risk ratio of postoperative subjective astigmatism ≥ 0.50 D by 2.2 (p<0.001). Conclusions: Preoperative objective astigmatism could not be directly interchanged with postoperative subjective astigmatism, but the presence of preoperative astigmatism ≥ 0.50 D doubled the risk of inducing a postoperative subjective astigmatism ≥ 0.50 D. Extra care when performing subjective refraction must be taken in the presence of high objective astigmatism.

To examine the relationship between corneal higher-order aberrations (HOAs), scatter, and residual refraction with visual symptoms and visual acuity after small-incision lenticule extraction (SMILE) for myopia and astigmatism. University Eye Clinic, Aarhus, Denmark. Prospective case series. Eyes had small-incision lenticule extraction for myopia or myopic astigmatism. Examinations were performed preoperatively and 1 day, 7 days, 1 month, and 3 months postoperatively and included subjective refraction, Pentacam HR measurements, scatter measurements (objective scatter index [OSI]), and questionnaires on visual quality and symptoms. The mean preoperative spherical equivalent (SE) was -7.08 diopters (D) ± 1.17 (SD). At 3 months, the mean uncorrected distance visual acuity (UDVA) was -0.03 ± 0.11 logarithm of the minimum angle of resolution and the mean SE, -0.17 ± 0.33 D; the OSI increased by a mean of 0.22 ± 0.53 (P = .06) and coma by 0.1 ± 0.1 μm (P < .001); spherical aberration did not change significantly. The severity of self-reported visual symptoms decreased postoperatively. Scatter, corneal HOAs, and residual refraction were not correlated with the degree of visual symptoms. On linear regression analysis, residual refraction was a significant predictor of UDVA (1 day: adjusted R2 = 0.16, P = .02; 3 months: adjusted R2 = 0.55, P < .001). Scatter and corneal HOAs were not associated with postoperative UDVA. Despite statistically significant changes in scatter and corneal HOAs, the severity of self-reported visual symptoms decreased postoperatively. Residual refraction was a good predictor of postoperative UDVA. Scatter and corneal HOAs had no effect on the postoperative UDVA.

Purpose: To investigate whether the Pentacam HR could accurately predict the surgically induced refractive change in patients operated with small‐incision lenticule extraction ( SMILE ) for myopia or femto‐second laser in situ keratomileusis ( FS ‐ LASIK ) for myopia or hyperopic astigmatism. Methods: Data from three groups consisting of (1) 410 myopic eyes of 410 patients operated with SMILE , (2) 111 myopic eyes of 111 patients operated with FS ‐ LASIK , and (3) 40 eyes of 40 patients with hyperopic astigmatism operated with FS ‐ LASIK were retrospectively analysed. The change in manifest refraction due to surgery was compared with the objectively measured change in corneal power by the Pentacam HR in three different ways: Sagittal Power (calculated as for placido topographers), True Net Power (calculated by a Gaussian optics formula), and Total Corneal Refractive Power (calculated by ray tracing). Multiple linear regression analysis was performed to investigate which parameters influenced the Pentacam HR 's prediction of the change in subjective refraction due to surgery. Results: The Total Corneal Refractive Power Apex, Zone calculation in a diameter of 4.0 mm effectively predicted the surgically induced refractive change for all three patient groups. The spherical equivalent was predicted with an error of 0.08 ± 0.41 D for the SMILE eyes, 0.05 ± 0.61 D for the myopic eyes operated with FS ‐ LASIK , and −0.15 ± 0.49 D for the hyperopic astigmatic eyes treated with FS ‐ LASIK . Regression showed that preoperative refractive error had a significant impact on the prediction error of the Pentacam HR . Conclusions: Ray tracing calculations based on Scheimpflug imaging accurately assessed the change in manifest refraction due to corneal laser surgery.