Early changes in corneal densitometry after FS-LASIK combined with accelerated corneal cross-linking for correction of high myopia

AIM:To observe the effects of femtosecond laserassisted excimer laser in situ keratomileusis combined with accelerated corneal cross-linking(FS-LASIK Xtra)on corneal densitometry after correcting for high myopia.METHODS:In this prospectively study,130 patients underwent FS-LASIK or FS-LASIK Xtra for high myopia.Their right eyes were selected for inclusion in the study,of which 65 cases of 65 eyes in the FS-LASIK group,65 patients with 65 eyes in the FS-LASIK Xtra group.Patients were evaluated for corneal densitometry at 1,3,and 6mo postoperatively using Pentacam Scheimpflug imaging.RESULTS:Preoperative differences in corneal densitometry between the FS-LASIK and FS-LASIK Xtra groups in different ranges were not statistically significant(P>0.05).Layer-by-layer analysis revealed statistically significant differences in the anterior(120μm),central,and total layer corneal densitometry between the FS-LASIK and FS-LASIK Xtra groups at 1 and 3mo postoperatively(all P<0.05),the FS-LASIK Xtra group is higher than that of the FS-LASIK group.Analysis of different diameter ranges showed statistically significant differences between the FS-LASIK group and the FS-LASIK Xtra group at 1mo postoperatively in the ranges of 0–2,2–6,and 6–10 mm(both P<0.05);At 3mo postoperatively,the FS-LASIK Xtra group is higher than that of the FS-LASIK group in the ranges of 0–2 and 2–6 mm(P<0.05).At 6mo postoperatively,there were no statistically significant differences in corneal densitometry between the FS-LASIK group and the FS-LASIK Xtra group in different diameter ranges(all P>0.05).CONCLUSION:There is an increase in internal corneal densitometry during the early postoperative period after FS-LASIK Xtra for correction of high myopia.However,the densitometry values decreased to the level of conventional FS-LASIK at 6mo after surgery,with the most significant changes observed in the superficial central zone.

Progress of corneal collagen cross-linking combined with refractive surgery

As a photochemical reaction that can stiffen the cornea,corneal collagen cross-linking(CXL) is the only promising method of preventing the progress of keratectasia,such as keratoconus and secondary ectasia following refractive surgery. The aim of CXL is to stabilize the underlying condition,with a small chance of visual improvement. Combining CXL with refractive surgery targeting both stabilization and reshaping of the corneal tissue for visual function improvement is a good treatment option. This review aims to provide a comprehensive and unbiased summary of the published research regarding combined CXL and refractive surgery,including measures and results,to help elucidate the future direction of CXL.

Experimental study on the treatment of rabbit corneal melting after alkali burn with Collagen cross-linking

AIM: To evaluate the effect of Collagen cross-linking on the prevention of melting in rabbit corneas after alkali burn. METHODS: Twenty New Zealand white rabbits were randomly divided into model control group and collagen cross-linking treatment group. The second group of rabbits received collagen cross linked treatment. Both groups were applied with antibiotic eye drops to prevent infection. The corneas were evaluated for melting, opacity, pathological and immunohistochemistry, record the changes when 28 days after the animals were killed. RESULTS: In the control group, 6 out of 8 rabbits showed corneal melting after injury (14 +/- 4) days, while two corneal perforated. In collagen cross-linking treatment group, one rabbit showed corneal melting after injury 23 days, without corneal perforation; corneal dissolution rate between the two groups was significantly different (P <0.05). Pathological examination suggested that in the treatment group, mild corneal edema, mild damage to collagen fibers, inflammatory cell infiltration was significantly less than the control group. Immunohistochemistry showed that corneal collagen fibers arranged in neat rows in the control group. CONCLUSION: Collagen cross-linking treatment not only can prevent and delay the corneal melting after alkali burn, but also can reduce the destruction of corneal collagen fibers and infiltration of inflammatory cells in the corneal tissue.

A short-term study of corneal collagen cross-linking with hypo-osmolar riboflavin solution in keratoconic corneas

AIM: To report the 3mo outcomes of collagen crosslinking(CXL) with a hypo-osmolar riboflavin in thin corneas with the thinnest thickness less than 400 μm without epithelium.METHODS: Eight eyes in 6 patients with age 26.2±4.8y were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution after its de-epithelization. Best corrected visual acuity, manifest refraction, the thinnest corneal thickness, and endothelial cell density were evaluated before and 3mo after the procedure.RESULTS: The mean thinnest thickness of the cornea was 408.5 ±29.0 μm before treatment and reduced to369.8 ±24.8 μm after the removal of epithelium. With the application of the hypo-osmolar riboflavin solution, the thickness increased to 445.0 ±26.5 μm before CXL and recover to 412.5 ±22.7 μm at 3mo after treatment, P =0.659). Before surgery, the mean K-value of the apex of the keratoconus corneas was 57.6 ±4.0 diopters, and slightly decreased(54.7±4.9 diopters) after surgery(P =0.085). Mean best-corrected visual acuity was 0.55 ±0.23 logarithm of the minimal angle of resolution, and increased to 0.53±0.26 logarithm after surgery(P =0.879).The endothelial cell density was 2706.4 ±201.6 cells/mm2 before treatment, and slightly decreased( 2641. 2 ±218.2 cells/mm2) at last fellow up(P =0.002).CONCLUSION: Corneal collagen cross-linking with a hypo-osmolar riboflavin in thin corneas seems to be a promising treatment. Further study should be done to evaluate the safety and efficiency of CXL in thin corneas for the long-term.

Corneal collagen cross-linking and liposomal amphotericin B combination therapy for fungal keratitis in rabbits

AIM： To observe the therapeutic effect of corneal collagen cross-linking（CXL） in combination with liposomal amphotericin B in fungal corneal ulcers.METHODS： New Zealand rabbits were induced fungal corneal ulcers by scratching and randomly divided into 3groups, i.e. control, treated with CXL, and combined therapy of CXL with 0.25% liposomal amphotericin B（n =5 each）. The corneal lesions were documented with slit-lamp and confocal microscopy on 3, 7, 14, 21 and 28 d after treatment. The corneas were examined with transmission electron microscopy（TEM） at 4wk.RESULTS： A rabbit corneal ulcer model of Fusarium was successfully established. The corneal epithelium defect areas in the two treatment groups were smaller than that in the control group on 3, 7, 14 and 21d（P 〈0.05）. The corneal epithelium defect areas of the combined group was smaller than that of the CXL group（P 〈0.05） on 7 and 14 d, but there were no statistical differences on 3, 21 and 28 d. The corneal epithelium defects of the two treatment groups have been healed by day 21. The corneal epithelium defects of the control group were healed on 28 d. The diameters of the corneal collagen fiber bundles（42.960 ±7.383 nm in the CXL group and 37.040±4.160 nm in the combined group） were thicker than that of the control group（24.900±1.868 nm）,but there was no difference between the two treatment groups. Some corneal collagen fiber bundles were distorted and with irregular arrangement, a large number of fibroblasts could be seen among them but no inflammatory cells in both treatment groups. CONCLUSION： CXL combined with liposomal amphotericin B have beneficial effects on fungal corneal ulcers. The combined therapy could alleviate corneal inflammattions, accelerate corneal repair, and shorten the course of disease.

Comparison of corneal biological parameters between transepithelial and epithelium-off corneal cross-linking in keratoconus

AIM:To evaluate the differences in corneal biological parameters between transepithelial and epithelium-off corneal cross-linking in keratoconus.METHODS:In our prospective clinical trial,40 patients(60 eyes)with progressive keratoconus were randomized to undergo corneal cross-linking with transepithelial(TE group,n=30)or epithelium-off(EO group,n=30)keratoconus.Examinations comprised topography,corneal biomechanical analysis and specular microscopy at 6 mo postoperatively.RESULTS:The keratometer values were not significantly different between the TE and EO corneal cross-linked groups in different periods(each P>0.05).The corneal thickness of the EO group was greater than that of the TE group at 1 wk after the operation(each P<0.05).Regarding corneal biomechanical responses,the EO group showed a longer second applanation length than TE group(P=0.003).Regarding the corneal endothelial function,standard deviation of the endothelial cell size,and coefficient of variation in the cell area,the values of EO group were larger than those of TE group at 1 wk(P=0.011,0.026),and the percentage of hexagonal cells in EO group was lower than that in TE group at 1 and 6 mo(P=0.018,0.019).CONCLUSION:Epithelium-off corneal cross-linking may strengthen corneal biomechanics better than TE procedure can.However,the TE procedure with a lower ultraviolet-A irradiation intensity would be safer for corneal endothelial function.

Surgical approaches to correct corneal astigmatism at time of cataract surgery: a mini-review

Among refractive errors,astigmatism is the most common optical aberration,where refraction changes in different meridians of the eye.It causes blurred vision at any distance and includes corneal,lenticular,and retinal astigmatism.Cataract surgery used to cause a progressive increase in the pre-exisiting corneal astigmatism because of creating a surgically induced astigmatism,for example,a large size surgery incision.The development of surgical techniques during last decades has made cataract surgery interchange to treat preoperative corneal astigmatism at time of surgery.Nowadays,three surgical approaches can be used.By placing a sutureless clear corneal incision on the steep meridian of the cornea,a preoperative corneal astigmatism less than 1.0 D can be corrected.Single or paired peripheral corneal relaxing incisions(PCRIs)provide 1.0-3.0 D corneal astigmatism correction.PCRIs are typically used for treating 1.0-1.5 D of regular corneal astigmatism,if more than 2.0 D,the risk of overcorrection and irregular astigmatism is increased.When toric intraocular lenses(IOLs)are unavailable in markets,PCRIs are still a reasonable option for patients with up to 3.0 D of pre-existing corneal astigmatism.Toric IOLs implantation can correct 1.0-4.5 D of corneal astigmatism.Several IOLs are approved to correct a high degree of corneal astigmatism with cylinder power up to 12.0 D.These approaches can be used alone or in combination.

Scheimpflug imaged corneal changes on anterior and posterior surfaces after collagen cross-linking

AIM:To compare the anterior and posterior corneal parameters before and after collagen cross-linking therapy for keratoconus.METHODS:Collagen cross-linking was performed in31 eyes of 31 keratoconus patients(mean age 30.6±8.9y).Prior to treatment and an average 7mo after therapy,Scheimpflug analysis was performed using Pentacam HR.In addition to corneal thickness assessments,corneal radius,elevation,and aberrometric measurements were performed both on anterior and posterior corneal surfaces.Data obtained before and after surgery were statistically analyzed.RESULTS:In terms of horizontal and vertical corneal radius,and central corneal thickness no deviations were observed an average 7mo after operation.Corneal higher order aberration showed no difference neither on anterior nor on posterior corneal surfaces.During follow-up period,no significant deviation was detected regarding elevation values obtained by measurement in mm units between the 3.0-8.0 mm-zones.CONCLUSION:Corneal stabilization could be observed in terms of anterior and posterior corneal surfaces,elevation and higher order aberration values 7mo after collagen cross-linking therapy for keratoconus.

Efficacy of iontophoresis-assisted epithelium-on corneal cross-linking for keratoconus

Corneal cross-linking（CXL） is a noninvasive therapeutic procedure for keratoconus that is aimed at improving corneal biomechanical properties by induction of covalent cross-links between stromal proteins. It is accomplished by ultraviolet A（UVA） radiation of the cornea, which is first saturated with photosensitizing riboflavin. It has been shown that standard epithelium-off CXL（S-CXL） is efficacious, and it has been recommended as the standard of care procedure for keratoconus. However, epithelial removal leads to pain, transient vision loss, and a higher risk of corneal infection. To avoid these disadvantages, transepithelial CXL was developed. Recently, iontophoresis has been adopted to increase riboflavin penetration through the epithelium. Several clinical observations have demonstrated the safety and efficacy of iontophoresisassisted epithelium-on CXL（I-CXL） for keratoconus. This review aimed to provide a comprehensive summary of the published studies regarding I-CXL and a comparison between I-CXL and S-CXL. All articles used in this review were mainly retrieved from the Pub Med database. Original articles and reviews were selected if they were related to the I-CXL technique or related to the comparison between I-CXL and S-CXL.

Trans-epithelial accelerated corneal cross-linking for keratoconus in children

The aim of the study is to evaluate the safety and effi cacy of trans-epithelial accelerated corneal cross-linking（TE-ACXL） in children with progressive keratoconus.Retrospective,case-series of 23 eyes of 14 children who underwent TE-ACXL.Evaluations were performed at baseline and 1,3,6,12 and 18 mo postoperatively.Mean follow-up time of 23.82±3.15 mo and mean age was 13.7±1.4 y（range 11 to 16 y）.Mean preoperative uncorrected distance visual acuity changed from 0.92±0.45 log MAR（20/160） to 0.71±0.40 log MAR（20/100）（P=0.001）.Mean keratometry（Km） changed from 53.87± 6.03 to 53.00±5.81（P=0.001）.Pachymetry did not have significant changes at last follow-up（P=0.30）.The mean preoperative sphere was-5.58±2.48 and-4.89±4.66 D（P=0.11） at last follow-up;refractive cylinder from-5.58±2.48 to-5.02±2.23（P=0.046）.In conclusion,tomographic and refractive stability are shown in over 91% of eyes with pediatric progressive keratoconus who underwent TE-ACXL.

A novel analysis of Scheimpflug total corneal refractive power following corneal cross-linking in mild to moderate keratoconus

AIM:To detect an earlier improvement in mild to moderate keratoconus following corneal cross-linking(CXL)with total corneal refractive power(TCRP)using ray tracing method.METHODS:A total of 40 eyes of 30 consecutive patients who underwent CXL for progressive keratoconus were retrospectively enrolled.The following keratometric parameters provided by Pentacam HR,including maximum keratometry(Kmax),steepest keratometry(Ksteep),3 mm zonal TCRP centered over corneal apex(TCRPapex,zone 3 mm),zonal mean keratometry and TCRP centered over corneal cone(Kmcone,zone and TCRPcone,zone 1,2,3 mm)were evaluated preoperatively and 1,3,6,and 12 mo postoperatively.Groups 1 and 2 were defined based on Kmax at postoperative 1 mo as improved(the initial improvement group)or worsen(the initial deterioration group)compared to the preoperative level.RESULTS:In the overall group,only keratometric parameters based on ray tracing method displayed significant improvement early at 3 mo postoperatively,in which TCRPcone,zone 1 mm and 2 mm exhibited the largest flattening(0.57 D and 0.53 D,respectively).In Group 1,only Kmax,Kmcone,zone 2 mm and TCRPcone,zone 2 mm showed significant improvement initially at 1 mo postoperatively,in which Kmax exhibited the largest improvement(1.05 D),followed by TCRPcone,zone 2 mm(0.82 D).In Group 2,only keratometric parameters based on ray tracing method and Kmcone,zone 3 mm showed slight but not significant improvement early at 3 mo,in which TCRPcone,zone 3 mm displayed the most improvement(0.19 D),followed by TCRPcone,zone 2 mm(0.15 D).CONCLUSION:The findings indicate that a 2 mm zonal TCRP centered over Kmax could earlier detect keratometric improvement by CXL compared to other commonly used parameters in mild to moderate keratoconic eyes.

Changes of matrix metalloproteinases in the stroma after corneal cross-linking in rabbits

AIM:To observe changes in the content of matrix metalloproteinases(MMPs)in the corneal stroma after corneal cross-linking(CXL)in rabbits,and further explore the corneal pathophysiological process after CXL.METHODS:Forty-two rabbits(42 eyes)were randomly divided into seven groups.One group served as the control group,while the other six groups were treated with CXL.The concentrations of MMPs in corneal stroma were evaluated through parallel reaction monitoring at baseline and 3,7,15,30,90,and 180 d after treatment.RESULTS:The levels of MMP-2 in the corneal stroma of rabbits were 0.76±0.07,2.78±1.39,4.12±0.69,2.00±0.29,2.00±0.30,1.22±0.18,and 1.35±0.18(10^(-9)mol/g)at baseline and 3,7,15,30,90,and 180 d after treatment,respectively.The contents of tissue inhibitor of metalloproteinase-1(TIMP-1)were 1.83±0.26,7.94±0.58,6.95±2.64,3.81±0.48,3.07±0.92,1.72±0.19,and 1.69±0.74(10^(-9)mol/g),respectively.The ratios of MMP-2/TIMP-1 were 0.42±0.33,0.36±0.20,0.62±0.10,0.54±0.15,0.68±0.13,0.71±0.10,and 0.68±0.09,respectively.After CXL,the expression of MMP-2 and TIMP-1 in the rabbit corneal stroma was initially increased and subsequently decreased.The levels of MMP-2 remained higher than those recorded at baseline 180 d after treatment,but it was not statistically significant.The levels of TIMP-1 returned to baseline levels at 90 d after treatment.The ratio of MMP-2/TIMP-1 started to rise from 7 d after CXL.It was significantly higher than that calculated at baseline 30-180 d after CXL.The results for MMP-1,-3,-7,-9,-13,and TIMP-2 were negative.CONCLUSION:CXL can lead to changes in the content of MMP-2 and TIMP-1 in the rabbit corneal stroma.The ratio of MMP-2/TIMP-1 remains higher versus baseline,indicating that MMP-2 is involved in the corneal pathophysiological process after CXL.

Analysis of the effective dose of ultraviolet light in corneal cross-linking

AIM: To analyze the efficacy of ultraviolet (UV) light initiating corneal cross-linking (CXL). METHODS: The time-dependent absorption of UV light due to the depletion of the initiator (riboflavin) was calculated. The effective dose of CXL with corneal surface covered by a thin layer of riboflavin was derived analytically. The cross linking time was calculated by the depletion level of the riboflavin concentration. A comprehensive method was used to derive analytic formulas. RESULTS: The effective dose of CXL was reduced by a factor (R) which was proportional to the thickness (d) and concentrations (C-0) of the riboflavin surface layer. Our calculations showed that the conventional dose of 5.4 J/cm(2) had a reduced effective dose of 4.3 and 3.45 J/cm(2), for d was 100 and 200 pm, respectively, and C-0=0.1%. The surface cross linking time was calculated to be T*=10.75s, for a depletion level of 0.135 and UV initial intensity of 30 mW/cm(2). The volume T* was exponentially increasing and proportional to exp (bdC(0)), with b being the steady state absorption coefficient. CONCLUSION: The effective dose of CXL is reduced by a factor proportional to the thickness and concentrations of the riboflavin surface layer. The wasted dose should be avoided by washing out the extra riboflavin surface layer prior to the UV light exposure.

Topography versus non-topography-guided photorefractive keratectomy with corneal cross-linking variations in keratoconus

AIM:To compare the visual results of non-topographyguided and topography-guided photorefractive keratectomy(PRK)applying sequential and simultaneous corneal crosslinking(CXL)treatment for keratoconus.METHODS:Interventional and comparative prospective study.Sixty-nine eyes(36 patients)suffering from keratoconus(stages 1 Amsler-Krumeich classification)were divided into four groups:sequential topography-guided photorefractive keratectomy with CXL,simultaneous topography-guided photorefractive keratectomy with CXL,simultaneous nontopography guided photorefractive keratectomy with CXL,and sequential non-topography guided photorefractive keratectomy with CXL.The main outcome measures were pre-and postoperative uncorrected distance visual acuity(UDVA),best corrected distance visual acuity(CDVA),manifest refraction,contrast sensitivity,and keratometry.RESULTS:All analyzed visual,contrast sensitivity,and refractive parameters showed a significant improvement in the four groups(all P<0.05).A noticeable improvement was seen in keratometry in all the groups,and a remarkable difference was observed between topography-guided groups in comparison to non-topography-guided groups(P<0.05).Interestingly,the improvement in all parameters showed a degree of stability to the end of the follow-up.CONCLUSION:The treatment priorities in all four groups are safety,efficacy,and predictability in the correction of the sphero-cylindrical errors in mild and moderate keratoconus.No significant differences among groups in the recorded objective outcomes were found.

Evaluation of corneal endothelium after UVA/riboflavin cross-linking in thin keratoconic corneas

Dear Sir,UVA/riboflavin cross-linking （CXL） has been used clinically applied for the treatment of keratoconus and corneal edema via enhancement of corneal stiffness The safety of the corneal endothelium is of prime importance during CXL treatment. In clinical practice, a corneal thickness （CT） of 400um has traditionally been regarded as the minimum treatable thickness, thereby avoiding damage to the corneal endothelium Although CXL has been applied to thinner corneas, using a hypoosmotic solution onto cornea and inducing edema . CXL safety still needs further evaluation because of lower relative concentration of collagen in the hydrated stroma . This study aims to evaluate the changes of corneal endothelial density （ECD） in cases where the CT is 〈400 um before iatrogenic corneal swelling and CXL treatment.

Corneal re-innervation following refractive surgery treatments

Laser refractive surgery is one of the most performed surgical procedures in the world. Although regarded safe and efficient, it has side effects. All of the laser based refractive surgical procedures invoke corneal nerve injury to some degree. The impact of this denervation can range from mild discomfort to neurotrophic corneas. Currently, three techniques are widely used for laser vision correction: small incision lenticule extraction, laser-assisted keratomileusis in situ and photorefractive keratotomy. Each of these techniques affects corneal innervation differently and has a different pattern of nerve regeneration. The purpose of this review is to summarize the different underlying mechanisms for corneal nerve injury and compare the different patterns of corneal reinnervation.

Correction of low corneal astigmatism in cataract surgery

· AIM: To evaluate and compare aspheric toric intraocular lens(IOL) implantation and aspheric monofocal IOL implantation with limbal relaxing incisions(LRI) to manage low corneal astigmatism(1.0-2.0 D) in cataract surgery.· METHODS: A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes(102 patients) with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were: visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III(Nidek Co, Japan). Follow-up lasted 6mo.· RESULTS: The mean uncorrected distance visual acuity(UCVA) and the best corrected visual acuity(BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group(P 【0.01). No difference was observed in the postoperative endothelial cell count between the two groups.· CONCLUSION: The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.

Clinical observation of removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis

AIM: To study the clinical observation of removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis. METHODS:A retrospective study was done to 10 patients (10 eyes) who had accepted removal of the necrotic corneal tissue combined with conjunctival flap covering surgery for fungal keratitis,the diagnosis by corneal scraping and smear examination or confocal microscopy check hyphae. Local and systemic antifungal therapy more than one week for all patients, corneal ulcer enlarge or no shrink. Slit lamp microscope examination the diameter of corneal ulcer about 2mm-4mm. Anterior segment optical coherence tomography (AS-OCT)examine the depth of corneal ulcer between 1/3-1/2, infiltrate corneal stroma about 20um-80um,the diameter of corneal ulcer about 3mm-6mm.Type-B ultrasonic exclusion endophthalmitis. Complete removal lesions until transparent of stoma, make conjunctival flap equal or greater than ulcer 1mm nearby conjunctiva. Continued antifungal therapy. The vision, fungal recurrence, conjunctival flap rollback or desquamate were analysed. ' RESULTS:Ten patients had success done this surgery, the corneal ulcer was not enlarge and healing afteroperation. 7 cases were bridging conjunctival flap and 3cases were single conjunctival flap. Preoperation vision above 0.1 had 8 cases,7 cases had vision above 0.1 one week after surgery, while 1 cases vision droped from 0.3 to 0.05.There was not recurrent for fungal,2 cases conjunctival flap rollback:1 case was bridging and 1case was single flap, no conjunctival flap desquamate. CONCLUSION: It is safe and effective to perform removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis which werenot sensitive or aggravate for antifungal drugs.

Changes of corneal central thickness of aphakia following congenital cataract surgery under the first six months of life

AIM: To observe the central corneal thickness (CCT) changes in infants and young children who had been undergone bilateral congenital cataract surgery, and to compare the changes with normal control group which was selected from healthy population. METHODS: A cross section case-control study contained 28 cases (56 eyes) of bilateral aphakia (aphakic group) due to congenital cataract surgery combining with posterior continuous curvilinear capsulorhexis and with anterior vitrectomy during 2-6 months after birth. Fourteen children (28 eyes) of age-sex matched with the aphalic group were selected as normal control group. CCT and intraocular pressure (TOP) were measured postoperatively and the results were compared between groups. RESULTS: The mean CCT was 653.5 +/- 82.4 mu m in the aphakic group and 579.6 +/- 39.2 mu m in the control group, with a significant difference (P=0.000). The mean value of TOP in aphakic group (22.0 +/- 1.6mmHg) was greater than that of control group (16.9 +/- 2.1mmHg), P=0.023. There was a negative correlation between age and CCT in normal control group (r=-0.531, P=0.026), and there was no correlation in bilateral aphakia group (r=-0.324, P=0.165). CONCLUSION: Aphakic children due to congenital cataract surgery have a greater CCT than normal children. It is necessary to consider CCT in evaluating IOP for children after congenital cataract surgery.

Comparing corneal outcome between femtosecond laser-assisted cataract surgery and conventional phaco surgery in Fuchs’endothelial dystrophy patients:a randomized pilot study with 6mo follow up

AIM:To compare the corneal outcome in Fuchs’endothelial dystrophy(FED)patients between femtosecond laser-assisted cataract surgery(FLACS)and conventional phaco surgery(CPS).METHODS:This was a randomized controlled study comparing one eye surgery by FLACS and the contralateral eye operated by CPS(stop and chop technique)in FED patients.Central corneal thickness,corneal light backscatter,corneal densitometry,and central corneal endothelial cell count and hexagonality(noncontact endothelial cell microscope),and corrected distance visual acuity(CDVA)were assessed preoperatively and at day 1,40,and 180 postoperatively.RESULTS:Totally 31 patients(16 women)were included.At day 40 postoperatively,the mean endothelial cell loss(ECL)was 23.67%by FLACS and 17.30%by CPS(P=0.53).At day 180 postoperatively,ECL was 25.58%in FLACS and 21.32%in CPS(P=0.69).Densitometry data in all layers and all annuli from anterior layer to posterior layer in annuli 0-2,2-6,6-10 and 10-12,total densitometry with all layers and all annuli was performed.A significant difference was found in 6-10(posterior layer)at day 1 with-1.42 grayscale units(GSU;95%CI:-2.66 to-0.19,P=0.02).In 10-12(anterior layer,central layer and all layers)at day 40 were significant different with 7.7(95%CI:1.89 to 13.50,P=0.009),3.97(95%CI:0.23 to 7.71,P=0.03),4.73 GSU(95%CI:0.71 to 8.75,P=0.02),respectively.In the remaining parameters we found no difference between the two groups(P>0.05).Three CPS eyes suffered from corneal decompensation.CONCLUSION:There is no significant difference in corneal outcome between FLACS and CPS.Endothelial cell density and pentacam corneal outcome may be inadequate as outcome parameters in FED patients.