Comparative Evaluation Of The Safety During 23-Gauge Vitrectomy With Scleral Incisions At 5.0 Mm Or 4.0 Mm Behind The Limbus

Part I Comparatively evaluation of the safety of the lens and the ora serrata during 23-gauge vitrectomy with scleral incisions at 5.0 mm or 4.0 mm behind the limbusObjective To observe the lens and ora serrata safety during 23G vitrectomy with sclera incisions at 5.0 mm or 4.0 mm behind the limbus.Methods A prospective case-controlled study was adopted.The data of 290 consecutive primary 23G vitrectomy patients(300 eyes)were enrolled in this study,all of which were phakic eyes.Amony them,146 patients(150 eyes)received 23G pars plana vitrectomy with scleral incisions at 5.0 mm behind the limbus.144 patients(150 eyes)received 23G pars plana vitrectomy with scleral incisions at 4.0 mm behind the limbus.All surgeries were performed by one surgeon at a single hospital.There were 87 males(89 eyes)and 59 females(61 eyes)in the 5.0 mm group,with the mean age of(56.36± 10.00)years and axial length of(23.97±2.47)mm.There were 76 males(78 eyes)and 68 females(72 eyes)in the 4.0 mm group,with the mean age of(54.65± 11.94)years and axial length of(24.20±2.26)mm.No statistically significant difference was found in age,axial length(t=-1.324,0.867,P=0.186,0.387)and in gender,right/left eyes,proportion of incidence(x2=1.366,2.615,10.195,P=0.242,0.106,0.07).Results Lens injury was observed in 4 eyes(2.67%)and in 14 eyes(9.33%)respectively in 5.0 mm and 4.0 mm group during surgery(x2=5.910,P=0.015);Retinal tears close to the scleral incision sites were observed in 5 eyes(3.33%)and in 6 eyes(4%)respectively in 5.0 mm and 4.0 mm group during surgery(x2=0.094,P=0.759).No other surgical complications occurred in both groups,such as retinal hemorrhage,supra-choroidal expulsive hemorrhage and iatrogenic retinal detachment.The time of removing the vitreous base was 3?16min(6.17±2.76 min)in 5.0 mm group and 4?35min(10.03±5.56 min)in 4.0 mm group(t=7.599,P<0.01).Conclusion Primary 23G pars plana vitrectomy with incisions at 5.0 mm posterior to the limbus is safe and efficient compared to that at 4.0 mm.Part ? Measurement of the scleral distances from the limbus to the plane passing through the lens posterior apex of the normal Chinese adultObjective To measure the normal Chinese adult parameter of the scleral distances from the limbus to the plane passing through the lens posterior apex.Methods The head CT scans of 105 patients without eye diseases in our hospital were studied during the same period of time for the vitrectomy surgeries in part one.The relationship between age,anteroposterior axis of eyeball,lens thickness and scleral distances from the limbus to the plane passing through the lens posterior apex was analysed with Pearson correlation analysis.Results Based on CT images,the average anteroposterior axis of eyeball,lens thickness and scleral distances from the limbus to the plane passing through the lens posterior apex was(24.39±0.97),(4.22±0.47),(6.72±0.81)mm,respectively.The results of Pearson correlation analysis showed that age had no relationship with anteroposterior axis of eyeball and scleral distances from the limbus to the plane passing through the lens posterior apex(r=-0.1173,0.1302,P=0.2332,0.1857);anteroposterior axis of eyeball had no relationship with scleral distances from the limbus to the plane passing through the lens posterior apex and lens thickness(r=-0.1470,0.0462,P=0.1347,0.6400);scleral distances from the limbus to the plane passing through the lens posterior apex had no relationship with lens thickness(r=0.0107,P=O.9140);age and lens thickness had statistically significant correlation(r=0.32 89,P=0.0006).Conclusion Scleral distances from the limbus to the plane passing through the lens posterior apex had no relationship with age,anteroposterior axis of eyeball and lens thickness when anteroposterior axis of eyeball is between 22.00 and 26.00 mm.Sclera incisions at 5.0 mm behind the limbus is suitable for the patients with anteroposterior axis of eyeball ranging from 22.00 to 26.00 mm.