Protecting the Corneal Endothelium

●Corneal Endothelium - The Challenge

●Claes Feinbaum Msc PhD

●Department of Ophthalmology

●Barzilai Medical Center

●Ashkelon, Israel

Protecting the endothelium during cataract surgery can be a

challenge for seasoned or novice surgeons alike depending on the

status of patients

Factors are as varied as the patients’ cases

Recognized non-corneal risk factors preventing injury to corneal endothelial cells:

1. Shallow A.C.

2. Crowded A.C.

3. Density of nucleus

4. Small pupils

5. Volume of infusion

6. Amount of ultrasound used

7. Type of IOL to be implanted

Corneal characteristics that may cause problems

1. Older patient age characterized by a lower endothelial cell density

and

2. Presence of Fuchs’ dystrophy and diabetes mellitus

Surgical factors to consider

●Decision making during the preoperative testing.

● In high-risk patients:

●1. Performing a cataract extraction

●or

●2. Descemet’s stripping endothelial keratoplasty (DSEK) triple procedure including:

●a. corneal transplant

●b. cataract removal

●c. IOL insertion

Patient symptoms duringpre-operative examination.

1. Severity of guttae (specular reflection)

2. Stromal edema

3. Lens density

4. A.C. Depth

5. Other symptoms

Examination should also include pachymetry and specular microscopy.

Phacoemulsification techniques and technology.

The phacoemulsification technique

1. Horizontal or vertical chop procedure reduces both energy used in eye and ultrasound time.

2. Benefits of ultrasound power modulation:

a. greatly reduced repulsion

b. decreased turbulence

c. enhanced followability

d. lower risk of thermal burns

e. less endothelial trauma

Resulting in less total energy used and less endothelial cellular loss at 6

months postoperatively

Phaco technology:Femtosecond-assisted cataract surgery

1. The effective phaco time can be reduced from about 1 minute to less than 30 seconds

2. From an average power of about 23.5% with phaco-only to about 13.5% with Femto

Use of viscoelastics.

Three types of viscoelastics are used in the eye depending on the patient:

Dispersives

Viscoat, Healon D, and Ocucoat

1. Have shorter chains

2. Coat the endothelium well

3. More difficult to remove

Cohesives

Healon, Healon 5, Provisc and Amvisc

1. Have longer chains

2. Easy to remove

3. Facilitate optimal visualization in the eye

Adaptives

Healon 5 and DiscoVisc

1. Cohesive under low-flow conditions

2. Dispersive in high-flow conditions

Irrigation and aspiration

Of Importance

Removing all nuclear fragments

Identify by slit lamp evaluation, gonioscopy, and ultrasound biomicroscopy

Most lens fragments found in the inferior angle

80% of patients with corneal edema diagnosed with lens fragment after day 1 postoperatively.

Intracameral medications.

Toxic anterior segment syndrome (TASS)

1. Onset 12 to 48 hours following cataract or anterior segment surgery

2. Sterile postoperative inflammatory reaction

3. Caused by a noninfectious substance entering the anterior segment

4. Causing toxic damage to the intraocular tissues

TASS Treatment

improves after treatment with corticosteroids

Ocular medications implications

1. Incorrect concentrations

2. pH

3. Osmolality; a vehicle with incorrect pH or osmolality

4. Preservatives in a medication solution

identified as causes.

Postoperative medications.

Medical Therapy

1. Instillation of corticosteroids prednisolone acetate 1% and difluprednate 0.05%

2. Newer delivery systems via nanoparticles and punctal plugs

3. Future medications such as Rho-kinase inhibitors

These were the pearls