The changes of axial length and corneal endothelial cell of overnight orthokeratology in adolescent with low to moderate myopia

We performed this study to evaluate the changes in refraction and axial length induced by intraocular silicone oil, and to compare with various clinical parameters between 1,000 and 5,000 cSt silicone oil. The refraction length was measured with an autorefractometer, and the axial length was measured with A-scan ultrasonography. These measurements were performed before and after removal of the silicone oil, using a clear cornea technique in which the silicone oil was injected in combination with pars plana vitrectomy. The mean age of the 25 patients was 38.73 years. On average the intraocular retention after the removal of the silicone oil lasted 5.13 months, and the follow-up time following silicone oil removal was 4.37 months. The changes in refraction and axial length were 6.32 diopters and 12.02 mm, respectively. Eyes injected with 5,000 cSt (11 eyes) tended to have higher changes in the refraction (5.84 vs 6.86 diopters) and axial length (11.70 vs 12.34 mm) than did eyes injected with 1,000 cSt silicone oil (14 eyes). Statistically significant differences were shown for the changes in refraction (p = 0.010) and intraocular pressure (0.63 vs 2.00 mmHg; p = 0.006), whereas but not for the changes in axial length (p = 0.306) and visual acuity (14/100 vs 15/100; p = 0.125). Intraocular silicone oil induced changes in refraction and axial length, and these changes seemed to vary with different viscosities.

The biometric changes of the human eye with lowered intraocular pressure (IOP), like those observed after glaucoma surgery, have been investigated by in vivo studies. Leydolt et al demonstrated IOP-dependent axial eye length changes in human eyes. An axial eye length decrease of 2 μm/mm Hg with short-term reduction of IOP was observed. They suggested that this concomitant shortening of axial length and IOP reduction could be a result of a decrease in scleral length owing to the reduced IOP or an increase in choroidal blood flow compensating the reduced ocular fundus pulsations during the increased IOP phase. In another in vivo study, Read et al showed that axial length underwent significant variation over a 24-hour period in normal human eyes, and a significant association existed between the change in axial length and the change in IOP, as measured by dynamic contour tonometry. The association observed between IOP and axial length was found to be consistent with the hypothesis of passive expansion and contraction of the globe in response to IOP. Studies on trabeculectomy patients, performed with or without cataract extraction, have shown a significant decrease of axial length after surgery, correlated with IOP reduction. Similarly, IOP lowering after tube shunt surgery may produce a decrease in axial length that is dependent on the amount of IOP lowering. Understanding how axial length changes impact clinical decisions, such as lens power choice for cataract surgery, is important for treating patients after glaucoma surgery or patients who have had previous glaucoma surgery. Table 41.1 summarizes reported axial length changes following different types of trabeculectomy procedures. Nemeth and Horoczi noted decreased axial length and increased thickness and volume of the ocular wall 4 days after trabeculectomy. In a retrospective study, Cashwell and Martin found a significant decrease in axial length (mean: 0.423 mm, range: 2.8 to +0.5 mm) after successful initial trabeculectomy in 62 patients using ultrasound biometry. Preoperative factors found to be associated with a greater decrease in axial length were young age, myopia, exposure to an antimetabolite, and a post-trabeculectomy IOP drop greater than 30 mmHg.

Clinical relevance Spectacle lenses with aspherical lenslets are effective in controlling axial elongation and slowing myopia progression in children with myopia, and its effectiveness may extend to children at risk of developing myopia. Background This study aims to examine the effectiveness of plano highly aspherical lenslets (HAL) spectacle lenses in slowing down axial elongation and spherical equivalent refraction (SER) progression among non-myopic children, using retrospective data records. Methods This retrospective study included data from medical records from an eye hospital network (Wellem Group) in Shanghai, China. Non-myopic children (non-cycloplegic SER between >-0.50 and ≤+0.75 D) aged 4–9 years, prescribed plano HAL lenses, were reviewed (N = 147). With available data prior to intervention, annualised changes in axial length and SER before and after wearing plano HAL lenses were computed. Effectiveness was evaluated with pre-treatment rates acting as controls, and differences in changes over time were calculated. Results A total of 105 non-myopic children were prescribed plano HAL lenses and had both pre-treatment and post-treatment visits (≥6 months). The mean ±SD age, SER, and axial length was 6.8 ± 1.3 years, 0.22 ± 0.29 D, and 23.1 ± 0.7 mm, respectively. The mean ±SE axial length and SER pre-treatment change was +0.44 ± 0.01 mm/year and −0.28 ± 0.03 D/year, respectively. After treatment, the mean axial length and SER change were +0.13 ± 0.01 mm/year and +0.14 ± 0.03 D/year, respectively. The mean difference in axial length and SER change over time was significantly different at −0.31 ± 0.02 mm/year and 0.42 ± 0.06 D/year, respectively (both p < 0.001). Lens wearing time was significantly associated with difference in axial length change over time (R2 = 0.19, p < 0.001). Conclusion Plano HAL lenses are effective in slowing axial elongation and SER progression among non-myopic children aged 4–9 years, which can potentially help in delaying myopia onset.

Given the agonistic nature of near work to promote axial elongation and the antagonistic nature of time outdoors to prevent myopia, we aimed to investigate the following: (a) how the short-term effect of near work performed outdoors (Experiment 1) influences axial length and (b) how near work performed in two different dioptric profiles (uncluttered and cluttered) alters the changes in central axial length (Experiment 2). Forty-six adults (age range: 19-32 years) participated in the study. In Experiment 1, 22 participants completed a 15-min distance task and a reading task in both the outdoor (~30,000 lux) and indoor (~70 lux) locations. In Experiment 2, 24participants performed the same reading task at a study desk in uncluttered and cluttered reading environments. Pre- and post-task ocular biometry measurements were performed for each session using a non-contact biometer. In Experiment 1, a significant increase in axial length from baseline was found after performing reading tasks in both outdoor (mean ± SEM: +12.3± 3.4μm, p= 0.001) and indoor locations (+11.9± 3.1μm, p= 0.001). In Experiment 2, axial length increased significantly from baseline to post reading task, in both uncluttered (+17.9± 3.5μm, p< 0.001) and cluttered reading environments (+19.2± 2.9μm, p< 0.001). No significant changes in axial length were observed either between outdoor and indoor locations (p= 0.92) or between the uncluttered and cluttered reading environment (p= 0.75). Independent of light intensity (outdoor or indoor location) and dioptric profile of the near-work environment (uncluttered or cluttered), a 15-min reading task led to a significant increase in axial length. While the long-term effects of these findings need to be evaluated, practitioners should emphasise how near work can reduce the beneficial effects of time outdoors, while providing recommendations related to time outdoors for myopia control.

Results of this randomized, double-masked clinical trial demonstrate the effectiveness of the MiSight soft contact lens in slowing myopia progression over multiple years. The purpose of this study was to quantify the effectiveness of MiSight daily disposable soft contact lens in slowing the progression of juvenile-onset myopia. Myopic children (spherical equivalent refraction, -0.75 to -4.00 D; astigmatism, <1.00 D) aged 8 to 12 years with no prior contact lens experience were enrolled in a 3-year, double-masked, randomized clinical trial at four investigational sites in four countries. Subjects in each group were matched for age, sex, and ethnicity and were randomized to either a MiSight 1-day contact lens (test) or Proclear 1-day (control; omafilcon A) and worn on a daily disposable basis. Primary outcome measures were the change in cycloplegic spherical equivalent refraction and axial length. Of the subjects enrolled, 75.5% (109/144) completed the clinical trial (53 test, 56 control). Unadjusted change in spherical equivalent refraction was -0.73 D (59%) less in the test group than in the control group (-0.51 ± 0.64 vs. -1.24 ± 0.61 D, P < .001). Mean change in axial length was 0.32 mm (52%) less in the test group than in the control group (0.30 ± 0.27 vs. 0.62 ± 0.30 mm, P < .001). Changes in spherical equivalent refraction and axial length were highly correlated (r = -0.90, P < .001). Over the course of the study, there were no cases of serious ocular adverse events reported. Four asymptomatic corneal infiltrative (one test, three control) events were observed at scheduled study visits. Results of this clinical trial demonstrate the effectiveness of the MiSight daily disposable soft contact lens in slowing change in spherical equivalent refraction and axial length.

Purpose This study aims to elucidate the longitudinal refractive and ocular biometric alterations in preschool children with high hyperopia who underwent early interventions. Methods We conducted a retrospective analysis of preschool children diagnosed with high hyperopia at Tianjin Medical University Eye Hospital between 2011 and 2023. Inclusion criteria required an initial examination with cycloplegic refraction, bilateral spherical equivalent power (SE) ≥ +5.00D with a difference <1.00D, a minimum two-year follow-up, and at least three ocular biometric measurements. The annual axial growth rate evaluated emmetropization in highly hyperopic children. We applied Restricted Cubic Spline (RCS) models to explore potential nonlinear relationships between age and spherical equivalent, axial length, corneal curvature, and axial length-to-corneal curvature ratio. Additionally, Mixed-effects models were employed to investigate factors associated with changes in refractive error and axial length. Results The study enrolled 60 eligible subjects, with a median initial diagnosis age of 3.5 years (IQR, 2.8-4.9 years) and a median last visit age of 9.3 years (IQR, 8.1-10.8 years). The average follow-up duration was 5.7 years. RCS analysis revealed notable nonlinear changes in spherical equivalent power, axial length, and axial length-to-corneal curvature ratio, although corneal curvature displayed no statistically significant nonlinear trend. Factors affecting SE changes included the presence of strabismus, the use of cycloplegia, baseline SE, and age. Conversely, changes in axial length solely correlated with baseline axial length and age. Conclusion Highly hyperopic preschool children undergoing early intervention display a marked emmetropization tendency, though most still remain moderately to highly hyperopic, with the progression of refractive changes showing non-uniform patterns with respect to age.

Monocular myopic defocus and daily changes in axial length and choroidal thickness of human eyes

Purpose To study the efficacy of low dose atropine (0.01%) eye drops in preventing myopia progression in children by comparing the mean change in spherical equivalent (diopter) and axial length (mm) over a period of one year to a control group and study its effect on near vision, pupil size, keratometry and pachymetry. Methods 200 eyes of 100 myopic children were randomized into two groups based on a computer-generated random number table. The treatment group was administered 0.01% atropine eye drop once at bedtime and control group was administered a placebo. The follow up was done 3-monthly for 12 months by assessing the mean change in spherical equivalent and mean change in axial length. Other parameters like near vision, pupil size, keratometry and pachymetry were assessed at each follow up. Result The study was age and sex matched. The mean change in spherical equivalent refraction and axial length was significantly lower in the treatment group (0.31 ± 0.55 D; 0.11 ± 0.22 mm) than the placebo group (0.80 ± 1.65 D; 0.23 ± 0.44 D) (p-value: 0.003). Less steepening of the corneal curvature was observed in the treatment group (0.16 ± 0.28 D vs 0.29 ± 0.3 D; p < 0.001) and the mean change in pachymetry was comparable between the groups (0.00 ± 0.01) (p-value 0.489). No significant change was seen in near vision (96% of the eyes with atropine had no change in near vision; 2% of the eyes had a change of near vision by one line (p-value 0.500); 2% had a change by 3 lines (p-value: 0.07) or pupil size following treatment. Conclusion The use of 0.01% atropine eye drop reduced the progression of myopia over the study period of one year with no significant changes in near vision, pupil size. No patient reported any systemic and local side effects with administration of 0.01% atropine eye drop.

To compare theoretical values from the small incision lenticule extraction (SMILE) lenticule thickness readout with change in axial length measurements taken with the IOLMaster. We prospectively studied 214 eyes from 107 patients undergoing bilateral SMILE surgery for myopia or myopic astigmatism between December 2014 and May 2017 at an ophthalmological practice in Singapore. All eyes were examined pre-operatively and 1 and 3 months post-operatively with the IOLMaster following SMILE surgery. Achieved lenticule thickness was taken as the change in axial length after surgery. A linear mixed-effects model was used to examine changes in axial length, spherical equivalent and acuity over time. The relationships between change in axial length and theoretical lenticule thickness and spherical equivalent were examined with multiple linear regression analyses, and model prediction was assessed with adjusted R2 statistics. Mean (95% confidence interval [CI]) spherical equivalent pre-operatively was - 5.25 (95% CI - 5.38 to - 5.12) diopters (D), at 1 month was 0.04 (95% CI - 0.09 to 0.17) D (p < 0.001), and at 3 months was - 0.02 (95% CI - 0.15 to 0.11) D (p < 0.001). Mean (95% CI) pre-operative axial length was 27,726 (95% CI 25,595 to 25,857) μm. Post-operative axial length at 1 month was significantly shorter at 25,595 (95% CI 25,464 to 25,726) μm (p < 0.001) with no change thereafter (p = 0.647). Pre-operative mean ± standard deviation (SD) refractive target was 0.24 (± 0.3) D, and mean difference between target and post-operative spherical equivalent at 1 month was 0.20 D (95% CI 0.16 to 0.25 D, p < 0.001). Multiple regression analysis showed that change in axial length at 1 month was, on average, 5% lower than theoretical lenticule thickness, indicating an average difference of 5.4 μm (95% CI 5.2 to 5.6 μm). Preoperative spherical equivalent predicted negative association with change in axial length at 1 month (β = - 14.8, 95% CI - 18.2 to - 11.3, adjusted R2 = 0.457, p < 0.001). Calculated lenticule thickness values were less than expected, and post-operative refractive outcomes at 1 month showed a slight under-correction. Further research in this area is needed to validate these findings.

PurposeTo determine the long‐term longitudinal axial length changes in myopic and hyperopic adults with an iris‐fixated phakic intraocular lens (pIOL).MethodsThe medical records of patients aged ≥18 years with myopia or hyperopia who were treated with pIOL implantation between 1996 and 2011 for refractive correction with a minimum follow‐up of 5 years after pIOL implantation were analyzed. The main outcome measure was change in ocular axial length over time.Results149 eyes of 149 myopic patients and 27 hyperopic eyes of 27 patients were included in this study. Mean patient age was 37.1 ± 10.4 years (35% male) in the myopic group and 39.4 ± 9.4 years (4% male) in the hyperopic group. The eyes of the myopic patients showed a significant mean increase in axial length of 0.45 ± 0.61 mm after a mean follow‐up time of 144 ± 38 months (p < 0.001). In 26 eyes (17%), the axial length had increased by ≥1 mm. The mean annual axial length increase was 0.04 ± 0.06 mm. Axial elongation was associated with a higher degree of myopia (p < 0.001) and younger age (p = 0.02). The eyes of the hyperopic patients showed no change in axial length over time.ConclusionsMyopic eyes corrected with an iris‐fixated pIOL show continuous increase in axial length at an adult age. Although this study is limited to subjects with a pIOL, this is the first time myopization in Caucasian adults has been reported in a large long‐term longitudinal study.

To investigate the influence of a short period of elevated IOP (induced through the wearing of standard swimming goggles) upon axial length. Forty young adult subjects (20 myopes and 20 emmetropes, mean age 22 ± 2 years) had their IOP and axial length measured before, during and after a 3 min period of swimming goggle wear. IOP was measured using a non-contact tonometer, and axial length with an optical biometer based upon the principle of partial coherence interferometry. A 3-min period of swimming goggle wear was found to be associated with a significant increase in IOP (mean change 3.7 ± 2.6 mmHg, p < 0.0001) and a significant axial elongation of the eye (mean change in axial length of 18 ± 12 μm, p < 0.0001). Both IOP and axial length were found to return to baseline levels upon removal of the swimming goggles. A significant positive association was found between the changes in IOP and axial length (r(2) = 0.37, p < 0.0001). There were no significant differences between the emmetropic and myopic subjects in terms of their magnitude of change in axial length and IOP during swimming goggle wear. A small magnitude of elevation in IOP, induced through mechanical means and imposed for a short period of time was associated with a small but statistically significant axial elongation of the eye.

Short-term axial eye length changes in response to imposed positive and negative defocus were compared in hyperopic, emmetropic and myopic young adults to learn about possible differences in emmetropization. Thirty-seven subjects (average age: 28±4 years) participated: emmetropes (n=15), myopes (n=15), and hyperopes (n=7). They viewed a 30-minute movie on a large TV screen (65″) at 2-meter distance (equivalent to -0.5D) with optical corrections, while a+3.5 D (myopic defocus) or -3.5 D (hyperopic defocus) lens was added in the right eye. A subset of myopes (n=14) was also tested with -2 D lenses. Axial length was measured in both eyes before and after viewing using the Haag-Streit Lenstar LS 900. With+3.5 D myopic defocus, emmetropes (-9.7±13.1µm) and hyperopes (-8.9±5.6µm) exhibited significant axial shortening, while myopes (-1.1±10.2µm) did not. Hyperopes and myopes differed significantly, but emmetropes and hyperopes did not. With -3.5 D hyperopic defocus, both emmetropic (+5.0±7.5µm) and hyperopic eyes (+6.6±6.9µm) elongated, indicating that their retina distinguished positive from negative defocus. Myopic eyes displayed paradoxical axial eye shortening (-7.1±8.6µm). Hyperopes and myopes differed significantly, but emmetropes and hyperopes did not. Reducing the lens power to -2 D abolished the shortening in myopes. Group data indicate bidirectional, sign-of-defocus-dependent axial length changes occur in both emmetropic and hyperopic eyes, indicating similar retinal function. Myopes showed reduced or even reversed responses, showing a functional deficiency in the myopic retina.

To investigate the influence of monocular hyperopic defocus on the normal diurnal rhythms in axial length and choroidal thickness of young adults. A series of axial length and choroidal thickness measurements (collected at ∼3 hourly intervals, with the first measurement at ∼9 am and the final measurement at ∼9 pm) were obtained for 15 emmetropic young adults over three consecutive days. The natural diurnal rhythms (day 1, no defocus), diurnal rhythms with monocular hyperopic defocus (day 2, -2.00 DS spectacle lens over the right eye), and the recovery from any defocus induced changes (day 3, no defocus) in diurnal rhythms were examined. Both axial length and choroidal thickness underwent significant diurnal changes on each of the three measurement days (p < 0.0001). The introduction of monocular hyperopic defocus resulted in significant changes in the diurnal variations observed in both parameters (p < 0.05). A significant (p < 0.001) increase in the mean amplitude (peak to trough) of change in axial length (mean increase, 0.016 ± 0.005 mm) and choroidal thickness (mean increase, 0.011 ± 0.003 mm) was observed on day 2 with hyperopic defocus compared to the two "no defocus" days (days 1 and 3). At the second measurement (mean time 12:10 pm) on the day with hyperopic defocus, the eye was significantly longer by 0.012 ± 0.002 mm compared to the other two days (p < 0.05). No significant difference was observed in the average timing of the daily peaks in axial length (mean peak time 12:12 pm) and choroidal thickness (21:02 pm) over the three days. The introduction of monocular hyperopic defocus resulted in a significant increase in the amplitude of the diurnal change in axial length and choroidal thickness that returned to normal the following day after removal of the blur stimulus.

To evaluate the incidence of symptomatic anisometropia and aniseikonia requiring intervention following surgery with combined pars plana vitrectomy (PPV) and broad 276 style encircling scleral buckle (ESB) for the repair of rhegmatogenous retinal detachments (RRD) and to report axial length (AL) and keratometry changes, a retrospective review of consecutive RRD patients treated with combined PPV and ESB between June 2016 until September 2019 was performed. All patients with symptomatic optically induced aniseikonia requiring additional interventions or surgical procedures including clear lens exchanges, secondary intraocular lens implants or contact lenses were documented. Keratometry and AL measurements were recorded for each eye and changes calculated. In total, 100 patients underwent combined PPV, ESB and endotamponade with mean age of 59.47 years (SD 11.49). AL was significantly increased (25.39 mm [SD 1.27] to 26.54 mm [SD 1.16], p = 0.0001), with a mean change of 1.15 mm (SD 0.67). Mean corneal astigmatism increased by –0.95 D (SD 0.51) in control eyes preoperatively and –1.33 (SD 0.87) postoperatively (p = 0.03). Over half of phakic patients (39/61; 64%) developed a visually significant cataract, subsequently undergoing surgery. Six of 100 patients developed symptomatic anisometropia with aniseikonia postoperatively (6%). Four proceeded with clear lens exchange despite absence of visually significant cataract (4%). Two of these initially trialled contact lenses (2%). One was intolerant, while the other decided to proceed with clear lens exchange for convenience. Only one patient (1%), being pseudophakic in both eyes, had persistent anisometropia/aniseikonia. AL and keratometry changes induced by encirclement with broad solid silicone rubber buckles are acceptable and similar to those reported previously using narrow encircling components, being unlikely to induce troublesome symptomatic anisometropia/aniseikonia. Many patients are phakic and develop visually significant cataracts, allowing correction of changes induced with the aim of visual restoration. A minority require more prolonged methods of visual rehabilitation, such as contact lens wear or clear lens exchanges. Caution and appropriate consent should be made in patients that are pseudophakic in both eyes at presentation.

The change in axial length in the pseudophakic eye compared to the unoperated fellow eye in children with bilateral cataracts