Volume 49 · Issue 04 · 2013

The femtosecond (FS) laser is a novel laser technology,and is approved clinical application by FDA in 2000.FS laser initially mainly used in corneal refractive surgery to replace the mechanical microkeratome.Since the accuracy and controllability of the FS laser is very high,it shows superiority in the field of corneal refractive surgery.And with the development of the relative hard and software,FS laser is began to used in other fields of ophthalmology,such as corneal transplants,cataract surgery,as well as assisted diagnosis et al.,although still have some limitations,the preliminary clinical results have been shown a very good prospects in the ophthalmology fields.Therefore,we reviewed the alternative applications,challenges and limitations,research direction in the future of FS laser,so that provide a reference and revelations for the peers. (Chin J Ophthalmol,2013,49:289-291)

To evaluate the safety,efficacy,predictability,stability and complications of femtosecond laser corneal small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism.

In this prospective study,50 patients (88 eyes) with myopia and myopic astigmatism were chosen to be performed SMILE procedure randomly.These patients were followed up at 1 day,1 week,1 month and 3 months postoperatively and were examined for uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),manifest refraction,intraocular pressure (IOP) and corneal topography.The results were analyzed with pairedttest,independent-samplesttest and regression analysis.

SMILE procedure was performed well in all patients,only 3 cases (3 eyes,3.4%) suffered from the suction loss,14 cases (26 eyes,29.5%) developed opaque bubble layer.All patients gained perfect UCVA (20/20),no eye had decrease of BCVA.The residual spherical equivalent was (-0.11±0.29) D,the astigmatism was (0.01±0.33) D 3 months postoperatively.The incidence of diffuse lamellar keratitis and haze was low,and no other complications were observed.The IOP was decreased slightly after 1 month (t=6.238,P<0.05),but no changes after 3 months (t=0.053,P<0.05).

The SMILE procedure is good at the safety,efficacy,predictability and stability for the correction of myopia and myopic astigmatism. (Chin J Ophthalmol,2013,49:292-298)

To evaluate and compare the recovery of central and peripheral corneal sensitivity in the early period after small incision lenticule extraction (SMILE) and femtosecond lenticule extraction (FLEx).

In this study,47 cases (87 eyes) which underwent SMILE and FLEx were included.Central,superior,inferior,nasal and temporal corneal sensitivity was measured using a Cochet-Bonnet esthesiometer (Luneau Ophthalmologie) before and 1 week,1 month,and 3 months after SMILE and FLEx.The results were analyzed with Mann-Whitney test by SPSS13.0 software.

There were statistical differences between SMILE and FLEx group in the central,inferior,nasal and temporal corneal sensitivity at 1 week,1 month and 3 months postoperatively (Z=-5.219,-7.120,-6.735,-7.139,-5.945,-6.644,-7.006,-7.121,-5.262,-3.086,-4.140,-3.523.P<0.01).However,the superior corneal sensitivity in the SMILE group did not show significant difference (Z=-1.807,P=0.071) as compared to FLEx group (with exception of 1 week postoperatively).At 1 month and 3 months postoperatively,corneal sensitivity in the superior quadrant were (5.23±0.62) and (5.57±0.57) cm in the SMILE group,and were (4.43±1.20) and (4.85±1.11) cm in the FLEx group.There were statistical differences between these two groups (Z=-2.935,-2.678.P=0.003,0.007).In the SMILE group,corneal sensitivity in the central,superior,inferior,nasal and temporal quadrants at 3 months postoperatively was (5.74±0.51),(5.57±0.57),(5.70±0.55),(5.83±0.37),(5.84±0.30) cm respectively,there were no significant differences as compared with preoperative data (Z=-1.255,-0.893,-0.570,-0.630,-0.935.P=0.209,0.440,0.569,0.529,0.350).In the FLEx group,corneal sensitivity in the superior at 3 months postoperatively was 4.85±1.11,there was not significant difference compared with preoperative data (Z=-1.095,P=0.272).There were no correlations between the changes of central corneal sensitivity and central corneal ablation depth,central corneal thickness and preoperative spherical equivalent (SMILE group:r=0.159,-0.202,0.106,0.060.P>0.05.FLEx group:r=-0.156,-0.059,0.058,-0.005.P>0.05) after SMILE and FLEx surgery.

Corneal sensitivity decreases after SMILE and FLEx,and then returns to its original state over time.The decrease of corneal sensitivity after the SMILE was fewer and the recovery was faster as compared with FLEx. (Chin J Ophthalmol,2013,49:299-304)

To determine flap thickness variation in 110μm thickness flap made by FS200 femtosecond laser and sub-Bowman keratiomileusis (SBK) microkeratome for studying the potential factors that affect the flap thickness.

It was a case-control study.Sixty patients were divided into two groups for laser in situ keratomileusis.The corneal flaps were made by using Alcon Wavelight FS200 femtosecond laser or MORIA SBK microkeratome.Central corneal flap thickness was calculated by subtraction pachymetry.Age,central corneal thickness (CCT),spherical equivalent refraction,mean keratometry and corneal diameter were recorded preoperatively for statistics.

This study comprised 120 eyes of 60 patients; 60 eyes were treated with each group.In Alcon Wavelight FS200 femtosecond laser group,the mean corneal flap thickness in the right and left eyes was (114.0±6.6) and (111.4±7.6) μm,respectively.The difference in corneal flap thickness between the right eye and the left eye (2.6±9.1) μm was not statistically significant (t=1.59,P=0.12).Corneal flap thickness had no relationship with the age,preoperatively CCT, spherical equivalent refraction,corneal curvature and corneal diameter through stepwise regression analysis.In SBK microkeratome group,the mean corneal flap thickness in the right eye and the left eye was (110.6±7.4) and (108.2±6.1) μm respectively.The difference in corneal flap thickness between the right eye and the left eye (2.4±6.6) μm was not statistically significant (t=2.019,P=0.054).Corneal flap thickness was positively correlated with preoperative CCT through stepwise regression analysis (r=0.29,P=0.021).Corneal flap thickness equaled to 67.77+ 0.076·CCT (F=5.63,P=0.021).Corneal flap thickness had no relationship with the age,spherical equivalent refraction,corneal curvature and corneal diameter.

Both FS200 femtosecond laser and SBK microkeratome can be used for making a good 110μm thickness flap.Central corneal flap thickness was positively correlated with the preoperative CCT using the SBK microkeratome. (Chin J Ophthalmol,2013,49:305-308)

To compare the incidence of posterior vitreous detachment (PVD) early after femtosecond laser and microkeratome-assisted LASIK and their changes after follow-up observation.

It was a prospective study.According to the choices of the patients,40 cases (80 eyes) underwent femtosecond laser (INTRALASE FS 60,Abbott Medical Optics,American) LASIK surgery in the femtosecond group and 40 cases (80 eyes) underwent microkeratome-assisted (AMADEUSⅡ,Ziemer,Switzerland) LASIK surgery in the microkeratome group.The occurrence of PVD was observed by B ultrasound and OCT examination pre-and 1 week,1,3 and 6 months postoperatively.Data from one eye in each patient were randomly selected for statistical analysis.Independent sampleχ²test was used to compare postoperative PVD between these two groups.Multiple logistic regression was used to investigate the association of PVD changes with age,gender,eye,axial length,refraction,IOP,corneal thickness and suction time.

In femtosecond group,18 eyes (45.0%) had partial PVD before surgery.In 11 eyes (27.5%),PVD developed in non-PVD eye or PVD increased in eyes already had PVD preoperatively.In microkeratome group,21 eyes (52.5%) had partial PVD preoperatively.In 8 eyes (20.0%),PVD developed in non-PVD eyes or PVD increased in eyes already had PVD preoperatively.There was no statistically significant difference between these 2 groups (χ²=2.257,P=0.133).Logistic regression analysis indicated that the suction time was associated with the postoperative development of PVD in femtosecond group (OR=1.089,P=0.027) and long axial length was a significant risk factor for the development of PVD in microkeratome group (OR=4.712,P=0.007).No serious posterior segment complications such as retinal breaks or retinal detachment were observed postoperatively.

INTRALASE FS60 femtosecond laser does not increase the incidence of PVD compared to AMADEUSⅡmicrokeratomeassisted LASIK.PVD is more likely to occur in eyes with long axial length.No serious posterior segment complications were observed during the 6 month follow-up period. (Chin J Ophthalmol,2013,49:309-314)

To investigate the risk factors of inadvertent cornea stromal dissection during mechanical epikeratome separation of the corneal epithelium using a Moria Epi-keratome and to explore the best procedure for the treatment of this complication.

We retrospectively reviewed inadvertent stromal dissections in central or peri-central areas of the cornea during mechanical epi-keratome separation of the corneal epithelium from a series of 708 eyes (355 patients) who received myopic Epi-laser-assisted in situ keratomileusis (Epi-LASIK) procedures during the past five years.The best spectacle corrected visual acuities (BCVA) and topographies at the final follow-up after the last procedures were compared.

From the total of treated eyes,4 eyes of 4 patients (0.56%) suffered inadvertent stromal dissection.In two of them,an excimer laser ablation under the flaps was performed immediately.One patient was treated with LASIK 6 month after the first procedure and another one received an excimer laser photo-therapeutic keratectomy (PTK) removing the corneal epithelium and photorefractive keratectomy (PRK) for refractive correction 1 month after Epi-LASIK.Postoperatively,BCVA lost one line in one eye which received immediate excimer laser ablation under complicated flap.Topography demonstrated irregularity corresponding to the site of stromal dissection.Two eyes (one received immediate excimer laser ablation and another received LASIK 6 month after stromal dissection) recovered to the pre-Epi-LASIK BCVA.One eye that received PTK and PRK 1 month after Epi-LASIK obtained an increase of one line in BCVA.Topography in all three eyes showed regular patterns in the middle of the cornea.

Stromal dissection during mechanical separation of the corneal epithelium with Moria Epi-K epikeratome is a potential complication of Epi-LASIK.One month postoperative PTK and PRK turned out to be the option of proper management for good recovery without severe visual impairment. (Chin J Ophthalmol,2013,49:315-319)

To investigate the clinical efficacy and safty of 0.1% bromfenac sodium hydrate ophthalmic solution in myopia and astigmatism eyes after sub-Bowman keratomileusis (SBK)

A case control study.Number of patients with low to moderate myopia (-6.00 D≤spherical equivalent<-2.00 D) in the test and control groups was 17 cases (32 eyes) and 20 cases (40 eyes),respectively.Number of patients with high myopia (-11.00 D≤spherical equivalent<-6.00 D) in the test and control groups was 22 cases (42 eyes) and 15 cases (26 eyes) respectively.The first day after SBK,0.1% bromfenac sodium hydrate eye drops was administrated 2 times/day in patients in the test group and continued for 10 and 14 days in low and high myopia,respectively.In the control group,0.1% fluorometholone eye drops was used 4 times/day,then reduced gradually and continuously for 16 days.Visual acuity,computer refraction,intraocular pressure (IOP) and corneal topography examination were conducted at different postoperative period.Symptoms and related complications were recorded.Ranked data were statistically analyzed using the Wilcoxon rank sum test and quantitative data were analyzed using independent samples t-test.

For low to moderate myopic patients,average postoperative IOP and corneal curvature K2 after one and three months in the test group were (7.84±1.35) and (8.13±1.75) mm Hg (1 mm Hg=0.133 kPa),and (38.66±1.68) and (38.75±1.45) D,respectively; in the control group,these parameters were (9.37±1.28) and (9.47±1.58) mm Hg and (39.56±1.58),and (39.51±1.50) D,respectively.All of these data in the test group were lower than those in the control group,the differences were statistically significant (t=-2.299,-2.112,P<0.05).There were no significant differences (P<0.05) in postoperative uncorrected visual acuity,spherical equivalent,corneal curvature K1,astigmatism CY,IOP (after 6 months) and corneal curvature K2 (after 6 months) between the test and control group.For the high myopic patients,mean postoperative uncorrected visual acuity in the test group and control group after 3 months were 5.14±0.06 and 5.09±0.07,respectively.The difference was statistically significant (t=2.517,P=0.015).There were no significant differences in symptoms between these two groups (two-sided testP>0.1).High IOP and obvious myopia regression were not found in all patients.

Bromfenac sodium hydrate eye drops (0.1%) can achieve the same therapeutic effect as fluorometholone eye drops after SBK and the former is better than the later in postoperative IOP control. (Chin J Ophthalmol,2013,49:320-326)

To investigate the clinical effects of special designed rigid gas permeable contact lens (RGPCL) in the treatment of secondary keratoconus.

Retrospective study.The results of correction of secondary keratoconus by the RGPCL in 89 cases (102 eyes) at the Optometry& Ophthalmology Center were analyzed,including history,slit lamp microscope,computer assisted corneal topography,phoropter,corneal endothelial cell examinations and A-scan corneal thickness measurements.We selected and designed the contact lens with different materials for refractive correction according to different corneal deformations.Visual stability and corneal changes were regularly observed.We compared corrected vision,corneal curvature and corneal topography before and after wearing spectacles and RGPCL by using a paired-t test.

Secondary keratoconus after keratorefractive operation in 56 cases (67 eyes),including post-LASIK in 53 eyes,post-PRK in 4 eyes and post-RK in 10 eyes were observed.The cornea thickness in the lesion region was less than 0.4 mm,with nebula or macula.Corneal topography showed different local protrusions,Steep K ranged 47.56 D to 69.72 D,corneal astigmatism ranged 4.00 D to 14.00 D,with irregular deformations,visible different degrees matrix strips pattern changes and Fleischer ring.Secondary keratoconus in 31 cases (31 eyes) was developed after corneal injury.The lesions included opaque scar,decrease of corneal endothelial density,multi-deformations and aphakia in 15 eyes.In addition,there were different degrees of damage in pupil,iris,vitreous and retina.Secondary keratoconus in one case (2 eyes) was developed after anti-glaucoma and pediatric cataract extraction operations (with intraocular lens implantation).Another case was secondary to repeated bilateral keratitis episodes,with large macula,mild thinning of cornea,neovascularization and roughness of corneal surface.The uncorrected visual acuity in these eyes was poor.After wearing the aspherical,Rose K,Piggyback and other special design of RGPCL made by high oxygen permeability materials,visual acuity could be raised to 4.9 or more in 90% cases.Corrected visual acuity remained stable and increased in some cases.Corneal topography showed that the corneal astigmatism,SRI and SAI values were reduced after wearing RGPCL,and the differences were statistically significant (t=2.389,2.645,2.255,P<0.05).

By using special designed RGPCL in secondary keratoconus after corneal refractive surgery or trauma,satisfactory corrected vision,flattened cornea and regular corneal shapes could be obtained. (Chin J Ophthalmol,2013,49:327-333)

To investigate whether the polymorphisms of insulin-like growth factor-1 (IGF-1) gene and its regulatory regions are associated with extreme high myopia.

A casecontrol analysis of 302 subjects with extreme high myopia and 401 controls was undertaken.Genomic DNA was obtained from peripheral blood.Seven tag single nucleotide polymorphisms (tSNP) across the IGF-1 gene region were selected to capture the majority of genetic variation.All tSNP were genotyped using the Mass Array platform and MALDI-TOF analysis.Genotypic distribution was tested for Hardy-Weinberg equilibrium.Statistical analyses were performed using the SPSS (version 13.0:SPSSScience,Chicago,IL) software.The genotype and allele frequencies were evaluated using theχ²tests and performed by Bonferroni corrections for multiple comparisons.The significance of the differences in the estimated haplotype frequencies between the myopia and control groups was examined on Haploview 4.2 usingχ²tests,and haplotypes were corrected by using permutation test after running 50 000 times.

Among seven different IGF-1 tSNP tested,the allele frequencies of four tSNP-rs5742629 (A/G),rs12423791 (G/C),rs35766 (G/A) and rs1457601 (T/A) in the myopia and the control groups were A (56.5%,62.3%) /G (43.5%,27.7%),G (70.4%,77.1%) /C (29.6%,22.9%),G (33.9%,28.8%) /A (66.1%,71.2%),T (72.5%,77.3%) /A (27.5%,22.7%),respectively.And they showed significant differences (χ²=4.968,8.059,4.250,4.245,P<0.05) between the two groups.However,only rs12423791 remained significance after Bonferroni correction.The haplotype GC of rs5742629-rs12423791 was associated with extreme high myopia (P=0.033) after 50 000 permutations for multiple comparisons as well.

The polymorphism of rs12423791 in IGF-1 may be associated with extreme high myopia in the Chinese population. (ChinJ Ophthalmol,2013,49:334-339)

e To compare the intraocular pressure (IOP) lowering effect of 0.004% travoprost and 2% carteolol in patients with ocular hypertension (OHT) after laser peripheral iridotomy (LPI) or trabeculectomy in primary angle-closure glaucoma (PACG).

Clinical case control trial.52 consecutive PACG patients (52 eyes) with IOP>21 mm Hg (1 mm Hg=0.133 kPa) after LPI or trabeculectomy were enrolled.24 patients received topical application of 0.004% travoprost (once daily) and 28 received 2% carteolol (twice daily).IOP lowering effect of travoprost and carteolol before and after treatment was measured by Goldmann tonometer and compared using t-test.The relationship of IOP lowering effect and the degree of angle open was performed by gonioscope and analyzed using Spearman rank correlation.

Compared with pretreatment,the IOP was significantly reduced in 24 patients (24 eyes) in 0.004% travoprost group[pre-treatment: (24.67±3.08) mm Hg,post-treatment: (18.58±2.71) mm Hg;t=6.600,P<0.05],while significantly reduced in 28 patients (28 eyes) received 2% carteolol[pre-treatment: (23.57±1.60) mm Hg,post-treatment: (19.57±1.60) mm Hg;t=5.130,P<0.05].0.004% travoprost group is more significant in both quantity and percentage of IOP lowering than 2% carteolol (t=2.533,2.532;P<0.05).There was no correlation between the IOP lowering effect and the degree of angle open in both groups (0.004% travoprostr=0.145,0.009;P>0.05; 2% carteololr=0.090,0.183,P>0.05).

Both of 0.004% travoprost and 2% carteolol reduce IOP in patients with OHT after LPI or trabeculectomy in PACG.0.004% travoprost is more effective than 2% carteolol in IOP lowering.However,the decrease of IOP is not acted through the alteration of anterior chamber angle in both study groups. (Chin J Ophthalmol,2013,49:340-344)

To analyze the distribution and shifting trends of fungal culture specimens and assess the drug sensitivity in vitro.

Case series study.From January 2009 to December 2010,1302 specimens were collected.These specimens were cultured on potato dextrose agar medium under 28℃and 40% humidity for 3-8 days.Drug sensitivity of positive cultures were evaluated by K-B method.Chi-square test was used for the analysis.

In 1302 specimens,292 samples (22.4%) were culture-positive,in which 69.9% were isolated from the cornea,3.8% from the vitreous body,1.0% from the anterior chamber,0.7% from the conjunctiva,0.7% from palpebral margin and 24.0% from other parts of the eye.Culture-positive rate of 2009 and 2010 were 21.2% (135/637) and 23.6% (157/665) respectively with no statistically significant difference (χ²=1.092,P=0.296).Two peaks of culture-positive outcome appeared in May and November.Culture results showed thatFusarium sp.was the commonest pathogen (59.6%,174/292),Aspergrium sp.in 16.8% (49/292) and Alternaria sp.in 10.6% (31/292).Patients from 31 to 60 years old accounted for 82.2% (240/292) of positive cases.The sensitive rate in vitro to natamycin,terbinafine,fluconazole,amphotericin B and itraconazole was 94.0% (63/67),63.4% (154/243),6.0% (17/285),39.7% (98/247) and 21.2% (65/306),respectively.

The top three commonest fungus of Beijing Tong Ren hospital successively are Fusarium sp.,Aspergrium sp.and Alternaria sp.Natamycin should be the first choice for fusarium infection and pathogen-unknown infection.All species with the exception ofFusarium sp.are sensitive to natamycin,terbinafine and amphotericin B but not itraconazole.Almost all fungal strains are resistant to fluconazole. (Chin J Ophthalmol,2013,49:345-349)

Gene engineering technology provides new methods for medical research.The application of transgenic animals and knock out animals makes it possible to study the biological characteristics of genes associated with some human diseases in vivo.Transgenic mice were first achieved in the early 1980 s,while they were used extensively in the field of ophthalmology doing some research a few years later after that.Therefore,it can possibly be a new path to investigate the pathogenesis by establishing transgenic mouse model of candidate gene of high myopia. (Chin J Ophthalmol,2013,49:377-380)

Neuroglobin (NGB) is widely exists in the retina and predominantly expressed in the plexiform layers and the inner segments.The physiological roles of NGB may include transportation of oxygen,protection against ischemia/hypoxia injury and oxidative stress,function as a redox-coupled sensor regulating the G-protein coupled transduction pathway,protection against neuronal apoptosis,and working as a terminal oxidase.Based on the function and distribution of NGB and the etiology and pathogenesis of retinal degeneration; it is possible that NGB may play a role in the development of retinal degeneration. (Chin J Ophthalmol,2013,49:381-384)