A retrospective study of cumulative absolute reduction in axial length after photobiomodulation therapy.

BACKGROUND: To assess the age and timeline distribution of ocular axial length shortening among myopic children treated with photobiomodulation therapy in the real world situations. METHODS: Retrospective study of photobiomodulation therapy in Chinese children aged 4 to 13 years old where axial length measurements were recorded and assessed to determine effectiveness at two age groups (4 ∼ 8 years old group and 9 ∼ 13 years old group). Data was collected from myopic children who received photobiomodulation therapy for 6 ∼ 12 months. Effectiveness of myopia control was defined as any follow-up axial length ≤ baseline axial length, confirming a reduction in axial length. Independent t-test was used to compare the effectiveness of the younger group and the older group with SPSS 22.0. RESULTS: 342 myopic children were included with mean age 8.64 ± 2.20 years and baseline mean axial length of 24.41 ± 1.17 mm. There were 85.40%, 46.30%, 71.20% and 58.30% children with axial length shortening recorded at follow-up for 1 month, 3 months, 6 months and 12 months, respectively. With respect to the axial length shortened eyes, the mean axial length difference (standard deviation) was - 0.039 (0.11) mm, -0.032 (0.11) mm, -0.037 (0.12) mm, -0.028 (0.57) mm at 1, 3, 6, and 12-month follow-up, respectively. Greater AL shortening was observed among the older group who had longer baseline axial lengths than the younger group (P < 0.001). CONCLUSIONS: Overall myopia control effectiveness using photobiomodulation therapy was shown to be age and time related, with the maximum absolute reduction in axial elongation being cumulative.

Photobiomodulation therapy retarded axial length growth in children with myopia: evidence from a 12-month randomized controlled trial evidence.

To determine whether photobiomodulation (PBM) therapy can retard ocular axial length (AL) in children with myopia. A randomized controlled clinical trial was conducted on two consecutive cohorts of 50 eligible children aged 8-12 years with ≤ - 0.75 Diopter (D) of spherical equivalent refraction (SER). Participants were randomly assigned to the intervention group (n = 25) and treated with PBM therapy or the control group (n = 25) and treated with single vision spectacles only. At the 12-month follow-up, the changes in AL and cycloplegic SER from baseline were both compared between the two groups. In addition, the subfoveal choroidal thickness (SFChT), anterior chamber depth (ACD), and central corneal refractive power (CCP) were analysed at the 3-, 6-, 9-, and 12-month follow-ups, respectively. Among the 50 children, 78% were included at the final follow-up, with a mean age of 9.7 ± 1.5 years and a mean SER of - 2.56 ± 1.70. The mean difference in AL growth between the two groups at 12 months was 0.50 mm (PBM vs. Control, - 0.02 mm ± 0.11 vs. 0.48 mm ± 0.16, P < 0.001), and the mean difference in cycloplegic SER at 12 months was + 1.25 D (PBM vs. Control, + 0.28 D ± 0.26 vs. - 0.97 D ± 0.25, P < 0.001). There were no significant differences in any of the other parameters (including SFChT, ACD, and CCP) between the two groups at any time point. PBM therapy is an effective intervention for slightly decreasing the AL to control myopia in children.Trial registration: Chinese Clinical Trial Registration Number: ChiCTR2100043619. Registered on 23/02/2021; prospectively registered. http://www.chictr.org.cn/showproj.aspx?proj=121302 .

Ocular growth and metabolomics are dependent upon the spectral content of ambient white light.

Myopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.

[Riboflavin photoprotection with cross-linking effect in photorefractive ablation of the cornea]. / Fotoprotektsiya riboflavinom s effektom krosslinkinga pri fotorefraktsionnoi ablyatsii rogovitsy.

UNLABELLED: Photorefractive ablation is inevitably accompanied by oxidative stress of the cornea and weakening of its biomechanical and photoprotective properties. AIM: To validate the expediency of riboflavin use in photorefractive ablation for photoprotection of the cornea and cross-linking. MATERIAL AND METHODS: The effects of riboflavin use in photorefractive ablation was first studied in a series of in vitro and in vivo experiments performed on 56 eyes of 28 rabbits, and then on 232 eyes of 142 patients with different degrees of myopia. Biomechanical testing of corneal samples was performed with Zwick/RoellВZ 2.5/TN1S tensile-testing machine. Transepithelial photorefractive keratectomy (TransPRK) and femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) were performed on Wavelight-Allegretto200, MEL-80, and WaveLight-EX500 excimer laser systems and also VisuMax and WaveLight-FS200 femtosecond lasers. For preliminary examinations, an appropriate set of diagnostic tools was used. RESULTS: In vivo experiments have proved that, in the absence of conservative therapy, riboflavin is able to produce both photoprotective and cross-linking effects to the cornea. Corneal syndrome was thus reduced and re-epithelialization after TransPRK accelerated. Biomechanical testing of corneal samples revealed an increase in tolerated load from 12.9±1.4 N to 18.3±1.2 N (p=0.0002) and tensile strength from 8.6±1.7 MPa to 12.4±1.7 MPa (p=0.007). Clinical studies conducted in a group of patients with mild to moderate myopia have also confirmed the photoprotective effect of riboflavin at months 1-12 after TransPRK. There were no significant differences in uncorrected visual acuity (ranged from 0.80±0.16 to 0.85±0.15) and corrected visual acuity at baseline (0.83±0.14). Evaluation of the optical and refractive effect achieved after Femto-LASIK with riboflavin photoprotection in the fellow eye has shown that this technique is not inferior to the traditional one as to its refractive accuracy, but provides better maintenance of biomechanical and photoprotective properties of the cornea. CONCLUSION: Photorefractive ablation of the cornea with preliminary saturation of the stroma with riboflavin solution ensures its photoprotection and provides an additional cross-linking effect.

Changes in dopamine and ZENK during suppression of myopia in chicks by intense illuminance.

High ambient illuminances have been found to slow the development of deprivation myopia in several animal models. Almost complete inhibition of myopia was observed in chickens when intermittent episodes of high illuminance were alternated with standard office illuminance (50% duty cycle, alternate periods of 1 min 15,000 lux and 1 min 500 lux, continued for 10 h per day), or when illuminances were increased to 40,000 lux. Since the mechanisms by which bright light suppresses myopia are poorly understood, we have studied the roles of two well-established signaling molecules in myopia, dopamine and ZENK, in the chicken. In line with previous studies, we found that retinal dopamine release (as reflected by vitreal DOPAC content) was severely reduced during development of deprivation myopia. We found that illuminance of 15,000 lux, provided by quartz-halogen lamps, partially rescued the drop in retinal dopamine release. The finding is in line with the assumption that dopamine is involved in the light-induced inhibition of myopia. No differences in vitreal DOPAC were found when bright light was provided continuously or with 1:1 min alternating exposure with 500 lux. As previously described by others, wearing diffusers suppressed the expression of ZENK protein in glucagonergic amacrine cells (GACs) but neither continuous nor 1:1 min alternating bright to normal light could rescue the suppression of ZENK in GACs. While it is well known that light increases global retinal ZENK mRNA and protein levels, the changes of ZENK protein induced specifically in GACs by diffuser wear appear independent of light levels.

Structural response of human corneal and scleral tissues to collagen cross-linking treatment with riboflavin and ultraviolet A light.

High success rates in clinical trials on keratoconic corneas suggest the possibility of efficient treatment against myopic progression. This study quantitatively investigated the in vitro ultrastructural effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin and UVA light in human corneo-scleral collagen fibrils. A total of 30.8 × 2 mm corneo-scleral strips from donor tissue were sagittally dissected using a scalpel. The five analytic parameters namely fibril density, fibril area, corneo-scleral thickness, fibril diameter, and fibril arrangement were investigated before and after riboflavin-UVA-catalyzed collagen cross-linking treatment. Collagen cross-linking effects were measured at the corneo-scleral stroma and were based on clinical corneal cross-linking procedures. The structural response levels were assessed by histology, digital mechanical caliper measurement, scanning electron microscopy, and atomic force microscopy. Riboflavin-UVA-catalyzed collagen cross-linking treatment led to an increase in the area, density, and diameters of both corneal (110, 112, and 103 %) and scleral (133, 133, and 127 %) stromal collagens. It also led to increases in corneal (107 %) and scleral (105 %) thickness. Collagen cross-linking treatment through riboflavin-sensitized photoreaction may cause structural property changes in the collagen fibril network of the cornea and sclera due to stromal edema and interfibrillar spacing narrowing. These changes were particularly prominent in the sclera. This technique can be used to treat progressive keratoconus in the cornea as well as progressive myopia in the sclera. Long-term collagen cross-linking treatment of keratoconic and myopic progression dramatically improves weakened corneo-scleral tissues.

[Effect of infrared low-intensity laser therapy on orbital blood circulation in children with progressive short sightedness].

This work was designed to study effect of low-intensity infrared laser radiation (LIIRR) on orbital circulation in children with progressive progressive short-handedness. Parameters of the blood flow in the orbital artery, central retinal artery, and posterior ciliary artery were evaluated in a total of 88 patients at the age from 6 to 14 years. The study group (group 1) comprised 66 children with moderately severe progressive myopia (112 eyes), the control one (group 2) included 22 patients without visual disturbances (44 eyes). Patients of group 1 received physiotherapy for the treatment of significantly deteriorated hemodynamics in the orbital region. Indirect action of LIIRR on the orbital region promoted stabilization of short-handedness in 78.8% of the treated patients. It is concluded that the method described in this paper is clinically efficient and may be recommended for the prevention of progressive myopia in children.

Terapia fotodinámica con verteporfina en neovascularización coroidea después de cirugía refractiva / Photodynamic therapy with verteporfin in choroidal neovascularization after refractive surgery

Propósito: Analizar los resultados obtenidos usando TFD (terapia fotodinámica) con verteporfina como primera elección para tratar la NVC (neovascularización coroidea) subfoveal y yuxtafoveal en pacientes con miopía magna corregida mediante cirugía refractiva (laser-assisted in situ keratomileusis -LASIK- y lentes fáquicas de cámara anterior -LFCA-). Método: Se estudiaron catorce ojos que presentaban alta miopía a los que se les había realizado LASIK (siete casos) o implante de lente intraocular –LIO– (siete casos), que desarrollaron NVC y fueron tratados con TFD con verteporfína. Resultados: La media Mejor Agudeza Visual Corregida (MAVC) después de la cirugía fue 0,45 (DE: 0,17; rango: 0.2 a 0.8), con equivalente esférico residual (EER) -0,5 (DE: 1,8D; rango: 1 a 5,5D). La MAVC después de NVC fue 0,10 (DE: 0,19; rango: 0,025 a 0,7). NVC fue tratada con TFD (media de 2,0 DE: 0,8 tratamientos). La media MAVC mejoró hasta 0,22 (DE: 0,18; rango: 0;1 a 0,63) (EER -1,4 DE: 1,4D; rango: 0,5 a -4D). Las diferencias en EER después de cirugía refractiva y después de TFD, y las diferencias en MAVC antes y después de TFD no fueron estadísticamente significativas (p=0,82 y p=0,06, respectivamente, aplicada t de Student para datos apareados). Conclusiones: El empleo de TFD para el tratamiento de la NVC tras la cirugía refractiva permite mantener la MAVC sin inducir cambios en el equivalente esférico

Purpose: To analyze the results obtained with Photodynamic Therapy (PDT) to treat subfoveal and juxtafoveal Choroidal Neovascularization (CNV) in patients with high myopia corrected by Laser-Assisted in situ Keratomileusis (LASIK) or by implanting a Phakic Intraocular Lens (PIOL). Methods: We analyzed the results from 14 highly myopic eyes corrected by LASIK (seven cases) or by PIOL implantation (seven cases), which later developed CNV and were treated by PDT with verteporfin. Results: Mean Best Corrected Visual Acuity (BCVA) after refractive surgery was 0.45 SD 0.17 (range, 0.2 to 0.8), with residual spherical equivalent (RSE) -0.5 SD 1.8 D (range, 1 to 5.5 D). After CNV appearance, BCVA was 0.10 SD 0.19 (range, 0.025 to 0.7). CNV was treated in all cases by PDT (mean, 2.0 SD 0.8 treatments). After CNV closure, the mean BCVA improved up to 0.22 SD 0.18 (range, 0.1 to 0.63) (RSE -1.4 SD 1.4 D, range, 0.5 to –4 D). Differences in RSE after refractive surgery and after PDT, and differences between BCVA after CNV appearance and final were not statistically significant (p=0.82 and p=0.06, respectively, Student’s t test paired data). Conclusion: We consider that PDT is effective in achieving closure of CNV in myopic patients after refractive surgery without inducing changes in spherical equivalent (Arch Soc Esp Oftalmol 2008; 83: 539-544)

Radiotherapy for subfoveal neovascularisation associated with pathological myopia: a pilot study.

BACKGROUND/AIM: Limited treatments are available for this disease process. A pilot study was performed to determine the toxicity and efficacy of external beam radiotherapy for subfoveal neovascular membranes and subretinal haemorrhage associated with pathological myopia. METHODS: A randomised, prospective study was carried out on 39 patients with subfoveal neovascularisation associated with high myopia. 20 patients underwent radiotherapy and the remaining 19 were observed as a randomised comparison group. All patients were followed up for at least 24 months. Subfoveal choroidal neovascular membranes (CNVMs) were treated with a single lateral 6 MV photon beam to a dose of 10 Gy in five fractions over 5-7 days. Post-treatment measurements included corrected visual acuity, area of CNVM, and occurrence of radiotherapy related complications, and adverse reactions. To assess changes of area of CNVM, the initial (pretreatment) size of the CNVM was set to 100%, and all post-treatment measurements were normalised relative to the initial size. RESULTS: No significant acute morbidity was noted. There was no significant difference in age, sex, refractive error, visual acuity, and area of CNVM at baseline between the treatment group and control group. The mean change of the size of the CNVM for 2 years was 155% (SD 156%) in the treatment group and 249% (124%) in the control group. The increase in the size of CNVM in the treatment group was significantly smaller than that in the control group (p = 0.0452). In the treated eyes, the visual acuity before and 1 and 2 years after radiotherapy were 0.111 (22.2/200), 0.091 (18.2/200), and 0.086 (19.2/200), respectively. In the control eyes, visual acuity before and 1 and 2 years after the start of the follow up were 0.141 (34.2/200), 0.089 (17.8/200), and 0.063 (12.6/200). The patients in the treatment group showed no significant change for 2 years, and those in the control group showed a significant decrease in the visual acuity (p = 0.0033). The changes of logMAR of visual acuity for 2 years after the start of the follow up were +0.019 (0. 443) in the treatment group and +0.347 (0.374) in the control group. There was a statistically significant difference between them (p = 0. 0173). Multiple regression analysis on the treatment group showed that the most significant predictive variable for the visual acuity 2 years after the treatment was the combination of pretreatment visual acuity and refractive error. CONCLUSIONS: Radiotherapy appeared to have a favourable treatment effect in eyes with subfoveal neovascular membranes and haemorrhage associated with pathological myopia. Further investigation is needed to evaluate the efficacy of radiotherapy for subfoveal neovascularisation associated with pathological myopia.

[Use of low-energy laser irradiation in patients with progressive myopia]. / Primenenie nizkoénergeticheskogo lazernogo izlucheniia u patsientov s progressiruiushchei blizorukost'iu.

A method of infrared laser exposure at a wavelength 1.3 microns for the treatment of progressive myopia has been developed, permitting a contactless trans-scleral irradiation of the ciliary muscle. Laser stimulation was carried out in 117 patients (234 eyes) aged 7 to 16. By the end of the first follow-up year the mean values of the positive part of accommodation increased by 2.0 to 2.5 diopters in patients of all age groups. A reduction of the parameters of ocular function was recorded 6-12 months after laser stimulation, though they remained higher than initially. A repeated curse of therapy helped normalize accommodation reserve parameters again. Prestimulation rheographic coefficient in all the examinees was 2.7 +/- 0.03% on an average, after treatment it was 3.44 +/- 0.02%. Hence, ciliary muscle stimulation by infrared laser helps in the majority of cases stabilize clinical refraction.

Combined microwave heating and surface cooling of the cornea.

We investigated a nonsurgical means of reshaping the cornea to correct hyperopia, keratoconus, or myopia. The object was to heat the central stroma of the cornea to the shrinkage temperature of collagen, 55-58 degrees C. The heating device was an open-ended, coaxial, near-field applicator driven at 2450 MHz; it incorporates cooling of the cornea surface by flow of saline. We investigated the system theoretically by computing the 2-D, axisymmetric temperature distribution with the finite element method. We investigated the system experimentally by heating excised steer corneas. Histology showed the system could shrink the stroma to a depth of 0.6 mm while sparing the epithelium in 75% of cases; the diameter of shrinkage was 1.3 mm. Theory predicted a significantly deeper and narrower region of shrinkage than was observed.

[Laser puncture in the combined treatment of a weak degree of myopia in schoolchildren]. / Lazeropunktura v kompleksnom lechenii miopii slaboi stepeni u detei shkol'nogo vozrasta.

To increase effectiveness of treatment, the influence of laser puncture on some functional indices of myopic eyes has been studied. Comparative analysis of results after laser puncture used as an independent method in 45 children (85 eyes)--group I, and in a complex accommodation-convergence system, of the eye in 66 children (130 eyes)--group II, has shown that laser puncture has a positive influence on visual acuity and accommodation-convergence system. As compared with group I, in group II normalization of functional indices (reserves of accommodation, convergence and divergence) begins earlier and stability of the results obtained is higher.

[Transudative myopic maculopathy: pathogenetic validity and comparative effectiveness of laser interventions]. / Transsudativnaia miopicheskaia makulopatiia: patogeneticheskaia obosnovannost' i sravnitel'naia éffektivnost' lazernykh vmeshatel'stv.

The paper presents a retrospective (5-10 years) analysis of results of treatment in a group of patients (104 eyes) with "moist" myopic maculopathy and initial visual acuity from 0.04 to 0.3. Subretinal neovascular membranes were found in 59% of eyes. Localization of the membranes was subfoveolar in 48% of cases, parafoveolar--in 39%, extrafoveolar--in 13%, the size of them being to 300 micrometers in 28%, from 300 to 800--in 58%, more than 800--in 14% of cases. Comparative assessment of effectiveness of various kinds of laser coagulation, laser stimulation and conservative treatment has shown laser coagulation to be the most effective and pathogenetically substantiated method of treatment of neovascular membranes. The most resultant is laser coagulation by the type of "panmacular" in combination with radical laser coagulation of neovascular membranes (if they are present). The most radical is laser coagulation with preservation of a new point of gaze fixation, ensuring preservation of a rather high visual acuity, 0.3. Laser coagulation has a transient effect only in cases of myopic maculopathy without neovascular membranes. Conservative treatment is ineffective. Mechanisms of therapeutic action of laser coagulation and laser stimulation are discussed.

[The mechanism of action of laser stimulation of the eye]. / K mekhanizmu deistviia lazerstimuliatsii organa zreniia.

The mechanism of action of helium-neon laser stimulation has been studied in 26 eyes of 15 patients with dystrophic diseases of the eye and on the ground of 63 lymphangiographic investigations of the same patients. It was found that low-energy helium-neon laser stimulation (0.05-0.5 mWt/cm2) has a positive effect on restoration of visual functions. Lymphangiographic investigations have revealed a new biological phenomenon--activation of disturbed lymphatic flow under the action of a specially organized laser radiation. The results obtained confirm the earlier hypothesis (M. M. Krasnov et al., 1982) that under the action of laser radiation a normal physiologic system purifying the retina from disintegrated products is engaged into action.