ABSTRACT
Ocular accommodation refers to the process by which the ciliary muscle creates a clear image of the object in the retina by changing the refractive power of the lens. When the accommodation ability of the eye is insufficient, the imaging focus falls on the region behind the retina and hyperopic defocus is easily formed, resulting in axial growth and leading to the development of myopia, and it is found that most myopic patients usually have some accommodation dysfunction. Myopia has become a public health problem in China, and the prevalence of adolescents has increased dramatically. How to prevent and stop the occurrence and development of myopia is a major challenge. Previous studies have found that ocular accommodation dysfunction is associated with the occurrence and development of myopia, and the measurement of parameters related to accommodation function has certain guiding significance for the prevention and control of myopia. The purpose of this paper is to review the correlation between myopia and ocular accommodation function, with a view to providing new ideas for the prevention, control and treatment of myopia.
ABSTRACT
Background Phakic posterior chamber implantable contact lens (PPC-ICL) or phakic posterior chamber Toric implantable contact lens (PPC-TICL) implantation is an effective way for the correction of high myopia or high myopia with astigmia,but it often has residual myopic power.Excimer laser-assisted subepithelial keratectomy (LASEK) can correct the residual myopia following PPC-ICL or PPC-TICL,but its effectiveness and safety deserve attention.Objective This study was to analyze the clinical effectiveness and safety of LASEK for residual myopia after PPC-ICL implantation for extreme high myopia.Methods A prospective cases-observational study was performed,and written informed consent was obtained from each patient before any surgery.Fourteen eyes of 9 patients with residual myopia following PPC-ICL or PPC-TICL for the eyes with spherical equivalent refraction of ≥-20.00 D were collected in the Affiliated Hospital of Guizhou Medical University from July 2010 to March 2015,including PPCICL implantation in 8 eyes and PPC-TICL implantation in 6 eyes.LASEK were performed on the eyes to correct the residual myopic power.Uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),haze,the distance of intraocular lens to lens,corneal thickness,corneal topography,corneal endothelial cell counting,intraocular pressure (IOP) and fundus were examined and compared before and after surgery.The effectiveness and safety of the surgery were evaluated.Results The operation was smooth and no complication was found after surgery in all of the eyes.The UCVA and BCVA were significantly different in the eyes among before surgery,6 months after PPC-ICL implantation and 12 months after LASEK (F =31.360,1.778;both at P＜0.05),and the UCVA after LASEK was higher than BCVA before LASEK.The refractive powers were (-22.27-±4.29),(-3.75±2.25) and (-0.42±0.63) D before surgery,6 months after PPC-ICL implantation and 12 months after LASEK,showing a significant difference among them (F=46.370,P＜0.05),and the refractive power was considerably lower after LASEK than that before surgery and after PPC-ICL implantation (both at P＜0.05).No significant difference was found in IOP or corneal endothelial cell counting in operated eyes among before surgery,6 months after PPC-ICL implantation and 12 months after LASEK (F=1.663,1.055;both at P＞0.05).The distance of intraocular lens to lens was (0.69±0.26)mm in the eyes after LASEK and (0.71 ±0.29)mm in the eyes after PPC-ICL implantation,with no significant difference between them (t =0.192,P＞0.05).Conclusions PPC-ICL or PPC-TICL implantation for the correction extreme high myopia often remains a certain degree of myopia,and LASEK for the correction of residual refractive power is safe and effective.