| PURPOSE: To describe the variation in ocular biometry in the high myopia patientswith different visual acuity, and to find the characters and relationship of them; Todescribe the destruction of the outer retina microstructure using frequency-domainoptical coherence tomography (fdOCT) in the high myopia patients, and to find thecharacters and the relationship with the function damage of the high myopia; Tocompare3methods of axial length measurement, immersion B-scan, contact A-scan,and IOLMaster in patients with cataract.METHODS:(1) A total of324cases (604eyes) within40years old were divided intoA, B, C, D four groups in every10years of an age. Every group was divided into threesubgroups according to the refractive status (high myopia group/the normal controlgroup) and the best corrected visual acuity of the patients with high myopia (was ornot≥0.8points).The ocular biological parameters, including axial length(AL), anteriorchamber depth(ACD), lens thickness(LT), and vitreous chamber depth(VCD), cornealcurvature(CC), refraction power, central subfield thickness(CST) cube volume(CV),cube average thickness(CAT),and the retinal thickness of each partition, were measured.The variation and characters in ocular biometry in the high myopia patients withdifferent visual acuity, and the relationship of them were analyzed;(2) In another24cases monocular high myopic anisometropia, the ocular biological parameters andvisual function were compared with the opposite eye. The relationship of destruction ofthe outer retina microstructure and the reduction of visual function in patients with highmyopia.(3)To analyze the data of the102patients (167eyes), with cataract and acceptedthe phacoemulsification and fold-able lens implantation in our hospital from Jan. in2011to May in2012. They were divided into two groups by refractive status: high myopia group (-6.50D~-19.75D) and non high myopia group（+0.75DS~-5.75DS）.Themeasurement of axial length was performed by immersion B-scan, contact A-scan, andIOLMaster, respectively. Keratometric power were measured preoperatively byIOLMaster. And IOL power calculation was carried out according to SRK/T formula inthe basis of IOLMaster. Their refraction outcome were fellow-up three months afteroperation.RESULTS:(1) Biometric and refraction data were available for all the subjects. Thevariation in ocular biometry in the normal patients AL, ACD, LT, VCD, CC,refraction power, CST,CV,CAT,inner ring(S-inner, I-inner, N-inner, T-inner),outerring(S-outer, I-outer, N-outer, T-outer)were22.67mm~24.50mm,3.21mm~3.78mm,3.77mm~4.06mm,15.68mm~16.74mm,42.74D~43.76D,226.13μm~244.78μm,9.91mm3~10.13mm3,274.44μm~283μm,315.10μm~321.39μm (318.90μm~328.85μm,315μm~320.46μm,319.10μm~326.15μ m,306.70μm~309.54μm),278.62μm~280.75μm(283.73μm~285.85μm,265.31μm~270.60μm,302.90μm~304.33μm,262.90μm~266.93μm). With the growth of the age, the AL, VCD extend with the age growth, and thecorneal curvature change was correlated with refractive error change. Themacular volume and mean retinal thickness in10~20years to reach thehighest level, then decreased with aging. The AL, refraction power, VCD range of thehigh myopia patients with normal visual acuity (high myopia group1) were25.67mm~27.62mm,-6.78D~-9.91D,18.36mm~19.04mm, increasing with age. Thenumerical range was between the normal control group and the high myopiapatients without normal visual acuity (high myopia group2) in the same age group.By comparison, the patients in high myopia group2were with longer AL(26.65mm~29.91mm), higher refraction power range (-8.79D~-18.46D), deeper VCD(19.73mm~21.14mm), and the growth rate of them were significantly greater thanpatients in high myopia group1and normal control patients in the same age rangegroup. The CST had no significant difference between the high myopia and thenormal control group. The CV, CAT in high myopia1groups were between normalcontrol group and high myopia group2, and the difference compared with the high myopia group1was statistically significant (P <0.05).In all groups, the distribution ruleof the average RNFL thickness was superior, inferior quadrants> temporal quadrant>nasal quadrant. Compared with the normal control group, the retinal thickness of thedifferent sections in the high myopia group was with different degree of thinning,especially in the high myopia group2. The analysis of the correlation between visualacuity and the ocular biological parameters showed that the AL, refraction errors,VCD, CAT, VC were moderately correlated (︱r︱≥0.4, p=0.000); the average retinalthickness of inner ring, outer ring were weakly correlated (0.2≤︱r︱≤0.4, p=0.000).(2)In the24patients with anisometropia, the average BACV of the high myopia was0.64(the opposite eyes was1.13), the average refraction power was-12.22D(theopposite eyes was-2.13D), the average AL was28.39mm (the opposite eyes was24.56mm), the average VCD was19.56mm(the opposite eyes was16.398mm),and allthese difference was statistically (p<0.05). The measurement results from the dfOCTshowed that the CAT of the high myopia was significantly thinner than the oppositeeyes when the VC and CST was with no significant decrease. With the traditionalvisual electrophysiological examination, compared with the opposite eyes, wavelatency of P100in P-VEP was significantly delayed, and the amplitude was significantlydecreased(p<0.05). The results of the reaction of F-ERG in highly myopic eyes showedthat, only the amplitude of the a wave in the maximum response,the amplitude ofb wave in single cone,30Hz flashing response decreased significantly (P<0.05).In thereaction of mfERG in highly myopic eyes,compared with opposite eyes,the responsedensity of the ring1,ring2,ring3were decreased significantly (P<0.05).Theamplitude of P1wave was significantly decreased and the latency of N1wassignificantly delayed (P<0.05).The observation of retinal outer structure showedthat, there were58.3%(14/24) patients in high myopia eyes with destruction ofCOST/VM.(3)In the non high myopia group, the axial length was (23.33±1.13)mm by immersionB-scan,(23.25±1.05)mm by contact A-scan, and(23.36±1.14) mm by IOLMaster,respectively. There were no significant difference among the three methods. The mean absolute refractive error (MARE), three months after operation, within±0.50diopterand±1.00diopter were not significant difference among the three methods.In the highmyopia group, the axial length was (28.41±2.06) mm by immersion B-scan,(28.21±2.15）mm by contact A-scan and (28.38±2.04) mm by IOLMaster, respectively.There were no significant difference between immersion B-scan and IOLMaster(t=0.726, P=0.473).The axial length measured by contact A-scan was shorter than byimmersion B-scan(t=2.223,P=0.003) and IOLMaster（t=2.614, P=0.014）significantly.The mean absolute refractive error (MARE), three months after operation, within±0.50diopter in immersion B-scan and IOLMaster were not significant difference(χ2=0.06,P>0.05); in immersion B-scan and contact A-Scan were significant difference（χ2=5.67,P<0.05）; within±1.00diopter in immersion B-scan and IOLMaster were notsignificant difference(χ2=0.36, P>0.05); in immersion B-scan and contact A-Scan weresignificant difference（χ2=4.19, P<0.05).CONCLUSION:(1)The variation in ocular biometry in the high myopia patients mainlymanifested as the increasing AL processing with the age and the VCD was the mostimportant factor，especially in patients with high myopia with low visual acuity and therefractive power often larger than-10D. Measurements in the macular region ofthe eye structure, the CAT was the most sensitive parameters. The CAT wassignificantly thinner, the CV was significantly decreased, the retinal thickness of innerring was significantly thinner in high myopia patients, especially in patients with higherdegree myopia power. In monocular highly myopic anisometropia patients, theBACV decrease significantly compared with the opposite eyes. In thestructure parameters, the AL, VCD was significant different, and the CAT wassignificantly reduced, the thickness of the inner ring was obviouslythinner. Although there was no significant changes in CST in the high myopic eyes, butthe results of the visual electrophysiological examination showed degeneration of theobjective visual function, and the degeneration of the visual function related with thedestraction of the COST/VM.(3)The immersion B-Scan, which is as accurate as the IOLMaster, is another good choice to measure the axial length in high myopia withcataract. |
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