Clinical Study Of RGPCL In Correcting Irregular Astigmatism After Keratoconus Cross-linking

BackgroundThe keratoconus is a bilateral,asymmetric corneal dilatation disorder characterized by a conical dilatation of the central or paracentral cornea with thinning of the corneal stroma in the bulge region.It may be the onset of both eyes at the same time or in succession.It occurs before and after puberty and is an important cause of vision loss and highly irregular astigmatism.The keratoconus treatment has three main purposes:to stop the process of corneal dilation,improve the shape of the cornea,and reduce residual refractive error.At present,a single treatment method is difficult to achieve the above three therapeutic purposes,and many combination treatment programs are applied to the treatment of keratoconus.Early keratoconus can be corrected with spectacles or contact lenses.The rigid gas-permeable contact lens can reshape the irregular front surface of the cornea,improve the vision of the patient,reduce the aberration of the cornea,and obtain better visual quality.Riboflavin-induced UVA corneal cross-linking is a minimally invasive treatment that has recently emerged.It can effectively prevent keratoconus progression.When the cornea is exacerbated and it is impossible to obtain good vision through frame glasses or contact lens correction,the biomechanical strength of the cornea can be enhanced by riboflavin-induced UVA corneal cross-linking to prevent the further progression of the keratoconus.However,many patients with irradia-induced UVA corneal cross-linking still have highly irregular astigmatism that is difficult to correct.There have been no clinical studies on the effect of RPGCL on the correction of irregular astigmatism after riboflavin/UVA cross-linking in keratoconus patients.This study was conducted to investigate the clinical effects of RPGCL in correcting irregular astigmatism after UVA cross-linking induced by riboflavin in keratoconus and to explore the safety and efficacy of this method.PurposeTo observe the safety and effectiveness of RGPCL in correcting irregular astigmatism after corneal cross-linking induced by riboflavin/UVA in patients with keratoconus.MethodsRetrospective nonrandomized study.28 patients(39 eyes)with keratoconus treated with standard corneal collagen crosslinking in our hospital were enrolled in this study.Application of Coptibis eye drops for three days before surgery was performed in a sterile environment.After topical anesthetic drugs were applied to the eyes,the corneal scraper was used to remove the central corneal epithelium with a diameter of 9 mm.0.1%isotonic riboflavin solution was applied to the eye,every 5 minutes,for a total of 30 minutes.The corneal thickness was measured by OCT.The corneal thickness was ≥400um in all patients.Under the slit lamp,the cornea was completely infiltrated with riboflavin solution.After riboflavin in the anterior chamber flashed,it was irradiated with ultraviolet A rays.The energy setting of the cross-linker:UVA wavelength of 370 nm,energy density of 3 mW/cm2,irradiation distance of 5 cm,irradiation range of 9 mm from the central corneal epithelial area,irradiation time of 30 minutes,and every 5 minutes during irradiation 0.1%isotonic riboflavin solution.The energy setting of the cross-linker:UV A wavelength of 370 nm,energy density of 3 mW/cm2,irradiation distance of 5 cm,irradiation range of 9 mm from the central corneal epithelial area,irradiation time of 30 minutes,and 0.1%isotonic riboflavin solution was applied once every 5 minutes during the irradiation.Patients were treated with regular eye drops after riboflavin/UVA cross-linking.Postoperative patients were referred back in our outpatient department.From 1 to 3 months after surgery,the cornea was in good condition and RGPCL was tested.Regular follow-up of 12 months after RGP wearing was performed,recording unpaired eyesight,best corrected visual acuity,corneal endothelium,corneal maximum K value,flat K value,and steep K value before and after RGPCL were recorded for paired t examination.All data in the study were statistically analyzed using SPSS 19.0 software,and P<0.05 was considered statistically significant.Measurement data are expressed as mean ± standard deviation(x±s).The normality test was performed using the Kolmogorov Smirnov(K-S)test before and after the RGPCL fitting.After the test,the normal distribution data was analyzed using the paired t-test.Wilcoxon analysis was not applied to the normal distribution data.Result1.RGPCL adaptation time:All patients in this study were successfully wearing RGPCL once.All patients can tolerate RGPCL wearing early foreign body sensation,tearing and other symptoms,generally 7d to 28d to adapt,an average of 17d.Throughout the observationperiod,all patients’ corneas remained transparent,no corneal bacterial or fungal infection,no corneal neovascularization,no giant papillary conjunctivitis and other complications,RGPCL maintained a good fit.2.Visual acuity:Using paired sample t-test,the uncorrected visual acuity of the patient before RGPCL fitting was 0.87 ± 0.30,the best corrected visual acuity of the spectacles was 0.41 ±0.14,and the corrected visual acuity was 0.06 ±0.08 when wearing RGPCL for one year,and the difference was statistically significant.(P<0.05).3.The maximum K value of the corneaThe maximum K value of the cornea before RGPCL fitting was 52.74 ±3.94.The maximum K value of the cornea after wearing RGPCL 1 year was 51.90±4.03.The difference was statistically significant(t=2.82,P=0.027<0.05).4.Comeal endothelial countBefore the RGPCL examination,the corneal endothelium count was 3063.54±191.18.After the RGPCL was worn for one year,the corneal endothelium count was 3063.43±191.19.The difference was not statistically significant(P>0.05).ConclusionRGPCL correction of keratoconic riboflavin/UVA-induced irregular astigmatism after corneal cross-linking is significantly better than spectacles.