Analysis On Influencing Factors Of High Intraocular Pressure After Implantable Collamer Lens

Refractive error (RE, and most of them are myopia) is the most common cause ofimpaired vision clinically, and has a morbidity up to30%-45%. According to theinvestigative result from the ministry of education and ministry of health in2009, thenumber of myopia in China has increased to300million, and is still increasing. Currently,major operations performed on myopia include corneal refractive surgery and intraocularrefractive surgery. For mild and moderate myopia, corneal refractive surgery is asatisfactory treatment. But for high and ultra-high myopia, high refraction can result in thecorneal curvature of anterior surface changing greatly, and the contrast sensitivity functionwill decrease sharply, which will lead to low visual quality for patients. Therefore, forpatients who have thin cornea and high refraction, intraocular refractive surgery especiallyICL (implantable collamer lens), has its own advantage as its nodual point closer to theeyeballs’, better treatment effect, less damage to the corneal and no alteration of the cornealcurvature.However, with the increasing number of the cases, more clinic attention has drawn tothe postoperative complications. HIOP(high intraocular pressure) is a commoncomplication among them. Continuous high intraocular pressure could lead to retinalhemorrhage and cause visual disturbances. Severe cases even progress to optic atrophy andresult in blindness. So far, factors leading to high intraocular pressure after ICL are notclear, and only a few reports were available. Other than that, no further research was maderelating to its influencing factors and curative effects.Objective To observe and analyze high intraocular pressure after implantable collamerlens (ICL), to investigate influencing factors and the therapeutic efficacy, and to provideevidence for clinical treatment. Besides, mass screening factors and data by periodscorrelated with high intraocular pressure were compared and analyzed, and the results wereavailable for prevention and treatment of high intraocular. Methods1. Clinical data of79ICL patients (155eyes) were analyzed retrospectively，including36males and43females，aged18～46(27.84±6.54)years old，and followed-upfor6months post-operatively. IOP, uncorrected visual acuity, best corrected visual acuity,refractive diopter, slit lamp examination, gonioscope, central anterior chamber depth (ACD),lens thickness, axial length, vault and trabecular-iris angle were recorded.2. Two groups according to whether occurring high intraocular pressure after implantablecollamer lens(ICL) in early and middle period were divided. Influencing factors of highintraocular pressure in early stage and middle stage were identified by Independent-SampleTest analyses.3. Two groups according to whether occurring high intraocular pressure afterimplantable collamer lens (ICL) in stable period were divided. Influencing factors of highintraocular pressure in stable period were identified by univariate and multivariate logisticregression analyses.4. Patients with high intraocular pressure after implantable collamer lens(ICL) instable stage were treated and curative effects were evaluated according to the changes ofIOP and BCVA during pre-treatment and post-treatment.Results1. HIOP after ICL is one of the most important complications, which mostly occurredat3stages: early stage (24~48h after ICL), middle stage (3~30d after ICL) and late stage(1~3m after ICL, also called stable stage).2. The rate of HIOP occurred during early stage was12.26%. Of the eyes with HIOP,the corneal epithelium was edema and anterior chamber was inflammatory withTyndall(+～++).The main reason of HIOP was residual sodium hyalurantae in anteriorchamber, the minor reason is pupil retardancy without cutting iris hole. It is not closelyrelated to patients’ age, DR of pre-operation, lens thickness, axial length, ACD, TIA or vaultof post-operation.3. The rate of HIOP occurred during middle stage is13.55%, and its main cause wascorticosteroid-induced ocular hypertension, secondary cause is trabecular meshwork clearance blocked by inflammatory cells. The most patients’ IOP could return to normalafter stopping glucocorticoid and treatment of decreasing IOP.4. Eight patients (16eyes) experienced HIOP at stable stage post-operatively with anincidence of10.32%(16/155). Non-HIOP after ICL was found in71patients(139eyes).87.5%(14eyes) was treated with topical drops and received good results but surgery wasrequired for12.5percent (2eyes), which couldn’t be controlled with topical drops. ACD(pre-operation and post-operation), HIOP at middle stage, vault and TIA of post-operationwere closely related to HIOP at stable stage after ICL(P<0.05). Post-operative TIA was theindependent influencing factor for HIOP at stable stage after ICL. It is not closely related topatients’ age, gender, DR of pre-operation, astigmatism, TIA of pre-operation, lensthickness, axial length or HIOP at early stage.5. The IOP and BCVA pre-treatment were26.13±3.56mmHg and0.69±0.20beforetreatment and19.98±2.51mmHg and0.80±0.191week post-treatment,and17.58±2.30mmHg and0.84±0.19after following-up.There was significant differencebetween pre-treatment and1week post-treatment(P<0.05).also.there was significantdifference between pre-treatment and after following-up (6months post-treatment)(P<0.05).Conclusions1. HIOP after ICL mostly occurred at3stages. The major cause of HIOP at early stageafter ICL was due to the viscoelastic remained in aqueous humor, which would result intemporary HIOP. Secondary cause is pupil retardancy without cutting a iris hole. The majorcause of HIOP occurred at middle stage was corticosteroid-induced ocular hypertension.2.HIOP at stable stage after ICL may be related to not matching good enough betweenICL and eye ball，which induced chronic inflammation for a long time.3. Patients’ IOP should be monitored closely after ICL. For different reasons，differenttreatments were given, which will control IOP effectively and make sure to get a bettercurative effects.