| Part 1.Analysis of Posterior Corneal Surface Keratometry atDifferent Ages by PentacamBACKGROUND:With the growth of age,all parts of the human body tend to aging.The eyes are also organs of human.As the mainly refractive stroma of human eye,the change of the cornea when aging is a process of transition from conformal to counter regulation of astigmatism.The study of the changes in the human eye clearly has a significant effect in clinical diagnosis and treatment.At present,clinical research mainly focuses on the anterior corneal surface refractive power,which is most widely used.But there is difference between total corneal refractive power and anterior corneal surface refractive power.This difference is due to the posterior corneal surface power.Pentacam HR can help us to study the posterior cornea and the whole cornea more convenience than before.OBJECTIVE:To study the corneal refractive parameters by using the Pentacam HR Anterior Segment Analysis System to investigate whether the posterior corneal refractive power will change when aging and its effects.METHODS:A total of 275 patients who visited the Ophthalmology Department of the Second Affiliated Hospital of Guangzhou Medical University from May 2017 to April 2018 were included.Age from 18 to 40 Among them,there are 144(288 eyes)young patients in group A.77 of them(122 eyes)with corneal astigmatism ?1.00D(low astigmatism)were collected in the A1 group,the average age was(29.3±5.8)years old.The other 99 patients(166 eyes)with corneal astigmatism of 1.00 to 4.00(Medium astigmatism)were included in the A2 group,with an average age of(27.5±5.4)years old.131 elderly patients with 166 eyes were included in group B.83 Cases(101 eyes)with corneal astigmatism ?1.00D(low astigmatism)were collected in Group B1 with an average age of(71.3±8.5)years old.And 56 patients(65 eyes)with a corneal astigmatism of 1.00-4.00D(medium astigmatism)were included in Group B2 with an average age of(73.5±9.5)years old.Patients' corneal anterior and posterior surface refractive power and total corneal refractive power were examined by Pentacam HR system.Data were collected and analyzed.RESULTS: K1,K2 and Km of the corneal anterior,posterior surfaces and total corneal refraction keratometry in group A1 were(42.90±1.13)diopters(D),(43.54±1.15)D,(43.22±1.13)D;(-6.15±0.20)D,(-6.43±0.22)D,(-6.30±0.20)D;(42.47±1.17)D,(43.04±1.21)D,(42.75±1.18)D;K1,K2 and Km of the corneal anterior and posterior surfaces and total corneal refractive keratometry in group B1 were(43.88±1.55)D,(44.41±1.54)D,(44.14±1.54)D;(-6.25±0.35)D,(-6.52±0.32)D,(-6.39±0.31)D;(43.57±1.66)D,(44.26±1.65)D,(43.91±1.64)D.K1,K2 and Km of the corneal anterior and posterior surfaces and total corneal refraction keratometry in the A2 group were(42.62±1.29)D,(44.13±1.41)D,(43.37±1.32)D;(-6.13±0.19)D,(-6.53±0.22)D,(-6.33±1.97)D;(42.20±1.40)D,(43.65±1.53)D,(42.92±1.44)D;K1,K2 and Km of the corneal anterior,posterior surfaces and total corneal refraction keratometry in group B2 were(43.37±1.36)D,(44.90±1.34)D,(44.13±1.32)D;(-6.28±0.24)D,(-6.52±0.26)D,(-6.40±0.23)D;(43.20±1.47)D,(44.77±1.50)D,(43.98±1.43)D.In comparison between the A1 and B1 groups,and between the A2 group and the B2 group,there was statistically significant difference between the flat meridian,the steep meridian and the mean keratometry of the anterior corneal surface and the whole cornea,and also the flat meridian keratometry of the posterior corneal surface.The difference in posterior corneal surface steep meridian keratometry was not statistically significant.There was a positive correlation between the corneal anterior surface,total corneal K1,K2 and Km with age,and negative correlation between K1 and Km with age on the posterior surface of the cornea.CONCLUSION:The flat meridian,the steep meridian and mean keratometry of the anterior cornea surface,the flat,the steep meridian,and the mean corneal keratometry of total cornea increased when aging,and the posterior flat meridian of the cornea and the mean corneal keratometry decreases when aging,except the steep meridian keratometry of the posterior corneal surface didn't change.And the corneal astigmatism has no effect on the results above.Part 2.Analysis of the Impact of Corneal Posterior Surface Keratometry on the Measurement of Intraocular LensBACKGROUND:At present,Sim K(Simulated keratometry,measurement of the corneal anterior surface refractive power)is mainly used in the calculation of intraocular lens power for cataract patients in clinically performance.The effect of the corneal posterior surface refractive power often neglected.In the precision treatment of today,the corneal posterior surface refractive power may be an intraocular lens degree correction to improve the vision or visual quality for the patient.It is an important aspect worth investigating in the study of cataracts.OBJECTIVE:The Pentacam anterior segment analysis system was used to study the corneal refractive keratometry parameters,and the correction of corneal posterior surface refractive power to intraocular lens power was explored.METHODS:A total of 131 patients with 166 eyes(77 eyes in the right eye and 89 eyes in the left eye)aged from 49 to 88 years old of age-related cataract who visited the Ophthalmology Department of the Second Affiliated Hospital of Guangzhou Medical University from March 2018 to April 2018.With astigmatic degrees ?1.00D(low astigmatism)patients were included in group A.A total of 81 cases(101 eyes)(49 eyes in the right eye,52 eyes in the left eye)including 29 cases(34 eyes)of male and 53 cases(67 eyes)of female.Age(71.3±8.5)years old.Patients with medium astigmatism(degree of astigmatism of 1.00-4.00D)were included in group B,a total of 56 cases(65 eyes)(right eye 28 eyes,left eye 37 eyes),including 19 males(21 eyes),37 females(44 eyes),average age(73.5±9.5)years old.Data were collected and analyzed.RESULTS:The K1,K2,Km of corneal anterior,posterior,and total corneal refraction in group A were(43.88±1.55)D,(44.41±1.54)D,(44.14±1.54)D;(43.57±1.66)D,(44.26±1.65)D,(43.91±1.64)D.The intraocular lens power calculated by Sim K was(18.51±5.98)D.The intraocular lens power calculated by TCRP was(18.86±5.83)D.The K1,K2,Km of the cornea's anterior,posterior and total corneal refractive power in group B were(43.37±1.36)D,(44.90±1.34)D,(44.13±1.32)D,(43.20±1.47)D,(44.77±1.50)D,(43.98±1.43)D.The intraocular lens power calculated by Sim K was(19.40±5.89)D.The intraocular lens power calculated by TCRP was(19.53±5.67)D.In the group comparison,there was a statistically significant difference between the flat meridian keratometry and the steep meridian keratometry of the anterior corneal surface and the whole cornea in group A.There was no statistically significant difference in the diopter of intraocular lens between Sim K and TCRP,and also the Km.The difference between flat and steep meridian keratometry of the whole cornea and in the diopter of intraocular lens calculated by using Sim K and TCRP was not statistically significance.Collecting parameters data for analysis.A total of 97 eyes were selected form group A.Toric intraocular lenses were calculated by using Sim K and TCRP.47 eyes'(48.45%)Toric IOL model has changed,and 51 eyes'(51.55%)model was not change.A total of 60 eyes were selected form group B.Toric intraocular lenses were calculated by using Sim K and TCRP.29 eyes(48.33%)with different Toric IOL model,and 31 eyes(51.67%)was not changed in IOL model.The change of Toric IOL model calculated by using Sim K and TCRP was not statistically significant.A total of 62 eyes were selected form group A.The axial direction of Toric IOL calculated with Sim K and TCRP was(44.47±26.58)° and(53.73±40.94)°.A total of 60 eyes were selected form group B.The Toric IOL axis calculated by using Sim K and TCRP was(58.03±57.12)°,(61.87±58.22)°,the axial difference between the two groups was not statistically significant.CONCLUSION:In age-related cataract patients,it is different between the corneal anteriorsurface keratometry and the total corneal keratometry in patients with low astigmatism,and there was no difference between them in patients with moderate astigmatism,which proved that the posterior corneal surface became smaller with corneal astigmatism increased.Irrespective of the corneal astigmatism,it is not necessary to apply the whole corneal parameter to correct the intraocular lens power for normal intraocular lenses without correction of astigmatism.For the astigmatism-corrected intraocular lens,The model of Toric IOL is corrected by using total corneal keratometry as possible,and the axial placement does not require correction. |
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