in this retrospective case study , the clinical records of patients who underwent cataract surgery at our hospital from august , 2012 to december , 2013 were reviewed . patients were divided into four groups according to incision size ( 2.2 or 2.8 mm ) and with / without stromal hydration ; 15 eyes were assigned to each group . the procedures were performed under topical anesthesia by a single surgeon at inje university ilsan paik hospital . inclusion criteria were no ocular surgery history , absence of biomicroscopic signs of pseudoexfoliation , normal fundus examination and endothelial cell count of at least 2,000 cells / mm . phacoemulsification and intraocular lens implantation were performed as follows : a side - port incision was created and an ophthalmic viscosurgical device was injected into the anterior chamber and then the main clear corneal incision was made using a 2.2- or a 2.8-mm diamond blade in each group . phacoemulsification was performed using ozil ( alcon , fort worth , tx , usa ) torsional technology with an ultrasleeve on an infiniti phacoemulsification platform ( alcon ) . an intraocular lens ( ny-60 ; hoya , tokyo , japan ) was implanted using the cartilage and injector . corneal stromal hydration was applied in 15 randomly selected eyes in the 2.2- and 2.8-mm incision groups by placing the tip of a 25-gauge cannula in the side walls of the incision and gently irrigating balanced salt solution into the stroma . incision wounds were measured using as - oct ( 3d - oct 2000 ; topcon , tokyo , japan ) at 2 hours , 1 day , 1 week , 1 month , and 3 months postoperatively . the patients were asked to look straight ahead to the opposite side of the corneal incisions . incision length and incision angle were also measured and presence of epithelial gaping , endothelial gaping and descemet 's membrane detachment was evaluated . epithelial gaping was defined as crack of the limbal edge of the superior corneal wound surface , endothelial gaping as crack of the limbal edge of posterior corneal wound surface and descemet 's membrane detachment as separation of descemet 's membrane from the stroma ( fig . 1 ) . statistical analyses of endothelial gaping , corneal thickness and incision length were performed using spss ver . the independent sample t - tests were used to compare parameters between the two groups ( 2.2 vs. 2.8 mm , hydration vs. no hydration ) . paired t - tests were used to compare the series of postoperative values . a p - value < 0.05 was considered to indicate a significant difference . in this study 60 eyes of 48 patients were enrolled and each group was composed of 15 eyes that were randomly assigned . the average patient age was 64.26  12.68 years ( range , 50 to 77 years ) . no incidence of postoperative complications such as wound leaking or endophthalmitis was observed in the no stromal hydration group . in eyes with stromal hydration , corneal thickness at the clear corneal incision was 1,098.50  67.01 , 827.00  85.49 , and 722.00  23.20 m on operation day , 1 week , and 1 month after surgery , respectively . in eyes without stromal hydration , corneal thickness at the clear corneal incision was 1,003.17  22.44 , 929.14  67.10 , and 797.71  64.01 m on operation day , 1 week , and 1 month after surgery , respectively . on operation day , corneal thickness in the 2.2 mm hydration group was statistically significantly thicker than in the 2.2 mm no - hydration group ( p = 0.002 ) . however , at 1 week and 1 month postoperatively , corneal thickness in the 2.2 mm no - hydration group was statistically significantly thicker than in the 2.2 mm hydration group ( p = 0.035 , p = 0.022 , respectively ) ( table 1 and fig . endothelial gaping was statistically significantly larger in the 2.2 mm stromal hydration group than in the 2.2 mm no - hydration group only on operation day ( p = 0.041 ) . there was no difference between the two groups postoperatively . in eyes with stromal hydration , corneal thickness at the clear corneal incision was 1,138.29  54.18 , 872.86  103.93 , and 752.86  58.40 m on operation day , 1 week , and 1 month after surgery , respectively . in eyes without stromal hydration , corneal thickness at the clear corneal incision was 1,021.71  35.95 , 889.14  90.20 , and 760.14  57.51 m on operation day , 1 week , and 1 month after surgery , respectively . corneal thickness was statistically significantly larger in the 2.8 mm stromal hydration group than in the 2.8 mm no - hydration group only on operation day ( p = 0.001 ) . corneal thickness was not significantly different between the two groups ( 2.2 and 2.8 mm ) on operation day , 1 day , 1 week , 1 month , and 3 months after surgery . in eyes with the 2.2-mm incision , endothelial gaping was 169.58  72.72 , 80.46  59.73 , and 61.00  47.82 at 1 day , 1 month , and 3 months after surgery , respectively . in eyes with the 2.8-mm incision , endothelial gaping was 116.08  41.06 , 33.93  23.85 , and 0.00  0.00 m at 1 day , 1 month , and 3 months after surgery , respectively . at 1 day , 1 month , and 3 months postoperatively , endothelial gaping was statistically significantly larger in the 2.2-mm incision group ( p = 0.035 , p = 0.009 , and p = 0.008 , respectively ) . there was no significant difference between the two groups on operation day and 1 week after surgery ( p = 0.131 , p = 0.116 ) ( table 3 ) . in eyes with stromal hydration , corneal thickness at the clear corneal incision was 1,119.92  61.36 , 851.69  94.93 , and 738.62  46.75 m on operation day , 1 week , and 1 month after surgery , respectively . in eyes without stromal hydration , corneal thickness at the clear corneal incision was 1013.15  30.80 , 909.14  19.14 , and 778.93  61.63 m on operation day , 1 week , and 1 month after surgery , respectively . only on operation day , corneal thickness was statistically significantly larger in the stromal hydration group than the no - hydration group ( p = 0.002 ) . other parameters showed no significant difference between the two groups ( with or without stromal hydration ) on operation day , 1 day , 1 week , 1 month , and 3 months after surgery ( table 4 ) . corneal thickness was only significantly different between the 2 groups ( 2.2 and 2.8 mm ) at 3 months after surgery ( 770.67 vs. 706.33 m , p = 0.048 ) . in eyes with the 2.2-mm incision , endothelial gaping was 247.50  83.30 , 204.83  77.12 , and 100.00  65.88 m on operation day , 1 day , and 1 month after surgery , respectively . in eyes with the 2.8-mm incision , endothelial gaping was 157.14  63.60 , 114.57  46.80 , and 37.01  23.6 7 m on operation day , 1 day , and 1 month after surgery , respectively . in the 2.8-mm no - hydration group , day and 1 day and 1 month postoperatively ( p = 0.035 , p = 0.035 , and p = 0.035 , respectively ) ( table 5 ) . descemet 's membrane detachment was observed in 66.7% ( 10 / 15 eyes ) and 40.0% ( 6 / 15 eyes ) on operation day and 1 day postoperatively , respectively and gradually decreased in the 2.2-mm incision stromal hydration group . in the 2.2-mm no - hydration group , descemet 's membrane detachment was observed in 40% ( 6 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 13.3% ( 2 / 15 eyes ) , 0% ( 0 / 15 eyes ) , and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the 2.8-mm incision with stromal hydration group , descemet 's membrane detachment was observed in 40% ( 6 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 13.3% ( 2 / 15 eyes ) , and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the 2.8-mm no - hydration group , descemet 's membrane detachment was observed in 26.7% ( 4 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 13.3% ( 2 / 15 eyes ) , 0% ( 0 / 15 eyes ) , and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the stromal hydration group ( integrating 2.2- and 2.8- mm incision groups ) , descemet 's membrane detachment was observed in 53.3% ( 16 / 30 eyes ) , 33.3% ( 10 / 30 eyes ) , 20% ( 6 / 30 eyes ) , 13.3% ( 4 / 15 eyes ) and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the no - hydration group ( integrating 2.2- and 2.8-mm incision groups ) , descemet 's membrane detachment was observed in 33.3% ( 10 / 30 eyes ) , 26.7% ( 8 / 30 eyes ) , 13.3% ( 4 / 30 eyes ) , 0% ( 0 / 15 eyes ) and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . descemet 's detachment gradually decreased in all groups but without statistically significant difference between the two groups including all data from both incision sizes and with or without stromal hydration . in eyes with stromal hydration , corneal thickness at the clear corneal incision was 1,098.50  67.01 , 827.00  85.49 , and 722.00  23.20 m on operation day , 1 week , and 1 month after surgery , respectively . in eyes without stromal hydration , corneal thickness at the clear corneal incision was 1,003.17  22.44 , 929.14  67.10 , and 797.71  64.01 m on operation day , 1 week , and 1 month after surgery , respectively . on operation day , corneal thickness in the 2.2 mm hydration group was statistically significantly thicker than in the 2.2 mm no - hydration group ( p = 0.002 ) . however , at 1 week and 1 month postoperatively , corneal thickness in the 2.2 mm no - hydration group was statistically significantly thicker than in the 2.2 mm hydration group ( p = 0.035 , p = 0.022 , respectively ) ( table 1 and fig . endothelial gaping was statistically significantly larger in the 2.2 mm stromal hydration group than in the 2.2 mm no - hydration group only on operation day ( p = 0.041 ) . in eyes with stromal hydration , corneal thickness at the clear corneal incision was 1,138.29  54.18 , 872.86  103.93 , and 752.86  58.40 m on operation day , 1 week , and 1 month after surgery , respectively . in eyes without stromal hydration , corneal thickness at the clear corneal incision was 1,021.71  35.95 , 889.14  90.20 , and 760.14  57.51 m on operation day , 1 week , and 1 month after surgery , respectively . corneal thickness was statistically significantly larger in the 2.8 mm stromal hydration group than in the 2.8 mm no - hydration group only on operation day ( p = 0.001 ) . corneal thickness was not significantly different between the two groups ( 2.2 and 2.8 mm ) on operation day , 1 day , 1 week , 1 month , and 3 months after surgery . in eyes with the 2.2-mm incision , endothelial gaping was 169.58  72.72 , 80.46  59.73 , and 61.00  47.82 at 1 day , 1 month , and 3 months after surgery , respectively . in eyes with the 2.8-mm incision , endothelial gaping was 116.08  41.06 , 33.93  23.85 , and 0.00  0.00 m at 1 day , 1 month , and 3 months after surgery , respectively . at 1 day , 1 month , and 3 months postoperatively , endothelial gaping was statistically significantly larger in the 2.2-mm incision group ( p = 0.035 , p = 0.009 , and p = 0.008 , respectively ) . there was no significant difference between the two groups on operation day and 1 week after surgery ( p = 0.131 , p = 0.116 ) ( table 3 ) . in eyes with stromal hydration , corneal thickness at the clear corneal incision was 1,119.92  61.36 , 851.69  94.93 , and 738.62  46.75 m on operation day , 1 week , and 1 month after surgery , respectively . in eyes without stromal hydration , corneal thickness at the clear corneal incision was 1013.15  30.80 , 909.14  19.14 , and 778.93  61.63 m on operation day , 1 week , and 1 month after surgery , respectively . only on operation day , corneal thickness was statistically significantly larger in the stromal hydration group than the no - hydration group ( p = 0.002 ) . other parameters showed no significant difference between the two groups ( with or without stromal hydration ) on operation day , 1 day , 1 week , 1 month , and 3 months after surgery ( table 4 ) . corneal thickness was only significantly different between the 2 groups ( 2.2 and 2.8 mm ) at 3 months after surgery ( 770.67 vs. 706.33 m , p = 0.048 ) . in eyes with the 2.2-mm incision , endothelial gaping was 247.50  83.30 , 204.83  77.12 , and 100.00  65.88 m on operation day , 1 day , and 1 month after surgery , respectively . in eyes with the 2.8-mm incision , endothelial gaping was 157.14  63.60 , 114.57  46.80 , and 37.01  23.6 7 m on operation day , 1 day , and 1 month after surgery , respectively . in the 2.8-mm no - hydration group , endothelial gaping was statistically smaller on operation day and 1 day and 1 month postoperatively ( p = 0.035 , p = 0.035 , and p = 0.035 , respectively ) ( table 5 ) . descemet 's membrane detachment was observed in 66.7% ( 10 / 15 eyes ) and 40.0% ( 6 / 15 eyes ) on operation day and 1 day postoperatively , respectively and gradually decreased in the 2.2-mm incision stromal hydration group . in the 2.2-mm no - hydration group , descemet 's membrane detachment was observed in 40% ( 6 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 13.3% ( 2 / 15 eyes ) , 0% ( 0 / 15 eyes ) , and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the 2.8-mm incision with stromal hydration group , descemet 's membrane detachment was observed in 40% ( 6 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 13.3% ( 2 / 15 eyes ) , and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the 2.8-mm no - hydration group , descemet 's membrane detachment was observed in 26.7% ( 4 / 15 eyes ) , 26.7% ( 4 / 15 eyes ) , 13.3% ( 2 / 15 eyes ) , 0% ( 0 / 15 eyes ) , and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the stromal hydration group ( integrating 2.2- and 2.8- mm incision groups ) , descemet 's membrane detachment was observed in 53.3% ( 16 / 30 eyes ) , 33.3% ( 10 / 30 eyes ) , 20% ( 6 / 30 eyes ) , 13.3% ( 4 / 15 eyes ) and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . in the no - hydration group ( integrating 2.2- and 2.8-mm incision groups ) , descemet 's membrane detachment was observed in 33.3% ( 10 / 30 eyes ) , 26.7% ( 8 / 30 eyes ) , 13.3% ( 4 / 30 eyes ) , 0% ( 0 / 15 eyes ) and 0% ( 0 / 15 eyes ) on operation day , 1 day , 1 week , 1 month , and 3 months postoperatively , respectively . descemet 's detachment gradually decreased in all groups but without statistically significant difference between the two groups including all data from both incision sizes and with or without stromal hydration . as - oct has been used to evaluate shape and thickness of cataract incisions , investigate related problems such as epithelial gaping , endothelial gaping and descemet 's membrane detachment and assess early postoperative outcomes . in our study , as - oct was utilized to monitor patients for up to 3 months after surgery . in the immediate postoperative period , the structural integrity of a clear corneal incision is critical as a barrier against entry of contaminants into the anterior chamber via the tear film . fine et al .   reported that incisional stromal swelling persists for at least 24 hours after surgery , but the duration of stromal swelling after cataract surgery is uncertain . corneal thickness was shown to increase significantly at 1 week postoperatively in the presence ( vs. absence ) of stromal hydration , with no significant difference thereafter . in our patients with 2.2-mm incisions , however , at 1 week and 1 month postoperatively , corneal thickness was significantly decreased in hydrated patients ( p = 0.035 and p = 0.022 , respectively ) . stromal hydration is characterized by the lateral walls of the main incision with visible whitening of stroma . although corneal endothelium apparently absolves water content of stromal hydration , a complete understanding of the incisional dynamics in cataract surgery is lacking . these results imply the process of corneal wound recovery may be intensified and expedited by pumping water onto the corneal endothelium via stromal hydration . therefore , we presumed that corneal thickness may remain significantly thinner in the stromal hydration group after surgery . as previously demonstrated , we similarly detected other early postoperative imperfections of wound architecture , such as endothelial gaping , epithelial gaping and descemet 's membrane detachment . when comparing patients with 2.2- and 2.8-mm incisions ( without hydration ) on the day of surgery , 1 day , when a 2.2-mm incision was used ( p = 0.035 , p = 0.035 , and p = 0.035 , respectively ) . endothelial gaping is defined by a crack at the limbal edge of the posterior corneal wound surface , which may reflect posterior incisional wound damage . small incisions may be subject to mechanical damage posteriorly during phacoemulsification , with further damage when stretched by a large lens delivery system . therefore , we hypothesized that a 2.8-mm incision would cause comparatively less corneal damage in the early postoperative period . the small incision of mics may decrease wound leaks , astigmatism and postoperative infection rates , but phacoemulsification of a microincision generally increases the duration and intensity of ultrasound exposure , creates difficulty in handling and exacerbates endothelial cell loss . smaller incision size , by virtue of larger ultrasonic pulse duty cycle , lower aspiration flow and lower vacuum is associated with increased wound temperature , which may be damaging . in fact , we found that endothelial gaping was significantly larger in the early postoperative phase when a small incision was used . on the day of surgery , we observed descemet 's membrane detachment in 66.7% ( 10 / 15 ) of eyes with 2.2-mm incisions and stromal hydration , 40% ( 6 / 15 ) of eyes with 2.2-mm incisions and no stromal hydration , 40% ( 6 / 15 ) of eyes with 2.8-mm incisions and stromal hydration and 26.7% ( 4 / 15 ) of eyes with 2.8-mm incisions with no stromal hydration that gradually disappeared postoperatively in all instances . ( 51% ; 1.3- , 2.2- , and 2.75-mm incisions overall ) , and fukuda et al . although none of our data differed significantly based on patient subset , the rates of descemet 's membrane detachment observed with the use of a 2.2-mm incision were higher than previously reported . in our opinion , a 2.2-mm corneal incision may be more vulnerable intraoperatively and during incisional stromal hydration . first , the patient population was relatively small , only short - term postoperative evaluations were conducted and single oct scans were obtained for each eye . further studies are necessary to analyze the long - term structural impact of incision size and stromal hydration in cataract surgery . second , a difference of corneal thickness according to age or individual existed , but corneal thickness was not measured preoperatively , thus the difference of corneal thickness between the preoperative and postoperative periods could not be compared . third , vertical length from epithelial to endothelial entry was not measured preoperatively which may have an impact on endothelial gaping . in conclusion , an as - oct system was used to determine the relative vulnerability of a small ( 2.2-mm ) corneal incision during and after cataract surgery . small incisions may be stretched and damaged by large lens delivery systems or other surgical instrumentation and postoperative stromal hydration may be damaging . although smaller incisions reflect the latest trend , choosing a surgical technique suitable for the clinical setting is important . although a trend can exist , focusing on the trend can cause other inconveniences and problems . the flexibility of using appropriate surgical techniques for patients instead of being preoccupied with either a smaller or larger incision may be more helpful for conducting a safe and efficient cataract surgery .
purposeto analyze healing changes of corneal wounds of different corneal incision sizes with or without stromal hydration in cataract surgery using anterior segment optical coherence tomography.methodscataract surgeries were performed by a single surgeon and 2.2- and 2.8-mm corneal incisions were made using a diamond blade ( me-759 ; meyco , biel - bienne , swiss ) . 
 patients were divided into four groups according to incision size ( 2.2 and 2.8 mm ) , and with / without stromal hydration . 
 fifteen eyes were assigned to each group and incision wounds were measured using anterior segment optical coherence tomography at 2 hours , 1 day , 1 week , 1 month , and 3 months postoperatively . 
 corneal thickness , incision length and incision angle were measured and existence of epithelial , endothelial gaping and descemet 's membrane detachment was evaluated.resultsincision thickness was greater in the group with stromal hydration than in the group without on operation day ( p < 0.05 ) . 
 stromal hydration exerted greater influence in the 2.2-mm incision group than in the 2.8-mm incision group . 
 corneal thickness decreased more rapidly in the stromal hydration group than in the group with no hydration ( p = 0.022 ) . 
 endothelial gaping was greater in the 2.2-mm incision group than in the 2.8-mm incision group 1 day , 1 month , and 3 months after surgery ( p = 0.035 , 
 p = 0.009 , and p = 0.008 , respectively ) . 
 no other statistical significance was observed between the two groups ( 2.2 and 2.8 mm ) during follow - up regarding corneal thickness , epithelial gaping and descemet 's membrane detachment.conclusionscorneal wounds with a smaller incision could be more vulnerable to external stimuli such as stromal hydration and are less stable than those with a larger incision .