Evaluation Of UVA/Riboflavin Corneal Collagen Crosslinking For Advanced Progressive Keratoconus

PurposeTo evaluate the short-term efficacy and safety of UVA/riboflavin corneal collagen crosslinking(CXL)for advanced progressive keratoconus with preoperative maximum keratometry more than 65D.MethodsRetrospective nonrandomized study.47 patients(54 eyes)with progressive keratoconus treated with standard corneal collagen crosslinking in our hospital were enrolled in this study.Inclusion criteria:1.maximum keratometry no less than 65D,2.thinnest coneal thickness ? 340?m,3.No serious corneal scar,4.no other ocular or systemic diseases.The procedure was performed under sterile conditions.After topical anesthesia using proparacaine hydrochloride 0.5%eye drops,a diameter of 9 mm and thickness of 50?m corneal epithelium was removed with mechanical microkeratome.Then 0.1%riboflavin solution was applied every 3 minutes for 30 minutes.After ascertaining the presence of riboflavin in stroma and anterior chamber,corneal stroma thickness was measured with optical coherenece tomography(OCT,Cirrus HD-OCT 4000;Carl Zeiss Meditec Inc,Hacienda Drive,Dublin,USA).If corneal thickness was less than 400 ?m,0.1%hypoosmolar riboflavin which was generated by diluting vitamin B2-riboflavin-5-phosphate 0.5%with physiological salt solution was additionally administered every 10 seconds for 2 minutes until adequate thickness was achieved.Then the eye was irradiated with UVA light(370 nm,3.0 mW/cm2,UV-X illumination system version 1000,UVXTM,IROCAG,Zurich,Switzerland)for 30 minutes at a working distance of 5 cm and riboflavin solution was reapplied every 3 minutes.After CXL,therapeutic bandage contact lens was placed.Antibiotic eye drops was given 4 times daily for one week and fluorometholone eyedrop 0.1%was administrated 4 times a day for 4 weeks.Bandage contact lens was removed after epithelium recovered,typically 3 to 5 days postoperatively.Patients were examined regularly and followed up to 1 year postoperatively.All contact lens wearers were required to discontinue two weeks before all examinitions.Routine clinical examinitions comprised the measurement of maximum keratometry(Kmax),flat and steep keratometry,uncorrected distance visual acuity(UDVA)and corrected visual acuity(CDVA)in LogMAR value,slitlamp evaluation,thinnest corneal thickness(TCT)and endothelial cell counting(ECC).Results1.The maximum keratometry was 73.5 ± 7.2 D preoperatively and reduced to 70.9 ±6.0 D at month 6(P=0.000)and 70.2 ± 5.6 D(P=0.000)12 months after CXL with statistically significant difference.2.The flat K-reading remained stable throughout 1-year follow-up period.The steep and mean K-reading were reduced with statistically significance(P<0.05).3.Mean preoperative uncorrected distance visual acuity was 1.04 ± 0.29(logMAR),and improved to 0.99 ± 0.29(P=0.053)at 6 months and 0.96 ± 0.29 at 12 months follow-up(P<0.01).Compared with preoperative data,the difference of UCVA at 12 months was statistically significant.4.Mean corrected distance visual acuity was 0.72 ±0.26 before treatment,0.59±0.27(P<0.01)at 6 months and 0.55 ± 0.27(P<0.01)at 1 year treatment with statitical significance.5.Before treatment,the TCT was 408 ± 36 ?m,with epithelium,which reduced to 392 ± 37 pm at 6 months and 391 ± 35 ?m at 12 months after CXL.Compared with preoperative data,the differences were all statistically significant(P<0.01).6.The ECC remained stable without significance(P>0.05).7.While in two eyes(3.7%)of two patients,maximum K-vaule increased after CXL even 12 months after CXL.ConclusionsCorneal collagen crosslinking can halt the progression of advanced progressive keratoconus with high K-value effectively,postpone or even avoid corneal transplantation.52 eyes from the total of 54 eyes get nice results with significant decrease of K-value and improvement of visual acuity.So advanced progressive keratoconus should not been excluded from CXL.