Endothelial Cell Loss and Induced Astigmatism After Wound-directed and Wound-assisted IOL Injection

• Endothelial cell loss [ Time Frame: one month ] [ Designated as safety issue: No ]
  As measured by specular microscopy
• Best corrected visual acuity [ Time Frame: one month ] [ Designated as safety issue: No ]
  By manifest refraction
• Final incision size [ Time Frame: intraoperatively (day #0) ] [ Designated as safety issue: No ]
  measured with incision gauges before and after lens injection.

The purpose of this study is to determine if there is any difference in astigmatism (eye surface curvature) or corneal endothelial cell density (the inner cell lining of the eye surface) after two different methods for inserting a lens during cataract surgery.

Cataract surgery (removal of a cloudy lens) is currently performed through increasingly smaller incisions. Bimanual surgery, where two instruments are used to remove the lens, is performed through two 1.4 mm incisions. Typically, one of these incisions is enlarged to 2.2 or 2.4 mm in order that the IOL (artificial lens) can be inserted into the eye. Surgeons insert these lenses by placing a lens injector cartridge completely into the eye (wound-directed insertion) or by placing only the tip inside the incision (wound-assisted insertion). While wound-assisted insertion can be performed through slightly smaller incisions (2.2 mm versus 2.4 mm for wound-directed insertion), both methods of insertion cause some incision enlargement. There is some evidence that wound-assisted insertion can cause very short-term pressure within the eye to go up. Neither method is considered inferior or superior to the other, and the primary investigator (Dr. Kenneth Cohen) routinely uses both methods.

No studies have directly compared wound-healing characteristics between these two methods. We seek to compare differences in:

1. Surgically-induced astigmatism (changes in the corneal curvature from cataract surgery incisions.
2. Endothelial cell density loss. Endothelial cells line the inside surface of the cornea, and their overall density can be decreased by cataract surgery.
3. Best-corrected vision after surgery
4. Sizes of the incisions after lens injection

• Cataracts
• Cataract Surgery

• Active Comparator: Wound-assisted lens injection
  Wound-assisted lens injection is considered neither superior or inferior to wound-directed lens injection.
  Intervention: Procedure: Lens insertion during cataract surgery
• Active Comparator: Wound-directed lens injection
  Wound-directed lens injection is neither considered superior nor inferior to wound-assisted lens injection.
  Intervention: Procedure: Lens insertion during cataract surgery

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• Kamae KK, Werner L, Chang W, Johnson JT, Mamalis N. Intraocular pressure changes during injection of microincision and conventional intraocular lenses through incisions smaller than 3.0 mm. J Cataract Refract Surg. 2009 Aug;35(8):1430-6.
• Osher RH. Microcoaxial phacoemulsification Part 2: clinical study. J Cataract Refract Surg. 2007 Mar;33(3):408-12.
• Kohnen T, Klaproth OK. Incision sizes before and after implantation of SN60WF intraocular lenses using the Monarch injector system with C and D cartridges. J Cataract Refract Surg. 2008 Oct;34(10):1748-53.
• Ventura AC, Wälti R, Böhnke M. Corneal thickness and endothelial density before and after cataract surgery. Br J Ophthalmol. 2001 Jan;85(1):18-20.
• Masket S, Wang L, Belani S. Induced astigmatism with 2.2- and 3.0-mm coaxial phacoemulsification incisions. J Refract Surg. 2009 Jan;25(1):21-4.

Inclusion Criteria:

• Eligible patients include those who undergo uncomplicated cataract extraction surgery and IOL implantation by KLC.

Exclusion Criteria: Patients who:

1. suffer from diabetes and have more than mild background diabetic retinopathy,
2. have a history of intraocular surgery,
3. have a history of ocular trauma,
4. have known pathology of the cornea,
5. have a history of intraocular inflammation,
6. are unable to understand English,
7. are decisionally impaired,
8. are currently incarcerated, or
9. are less than 18 years of age.

No exclusions will be made on the basis of gender, ethnicity, or race.