4. WHAT IS CATARACT???
A cataract is a clouding of the natural intraocular crystalline
lens that focuses the light entering the eye onto the retina.
This cloudiness can cause a decrease in vision and may lead
to eventual blindness if left untreated.
Cataract can also be defined as complete or partial opacity of
the ocular lens.
4
5. PATHOPHYSIOLOGY OF CATARACT
The clear lens of the
eye transmits light rays
entering the eye and
focuses them on the
retina
With aging, lens proteins
progressively denature
causing increase in
density and yellowish-
brown coloration of the
lens
The resultant cloudy lens
lacks the ability to transmit
and focus light rays on the
retina
This manifests as blurry
vision or loss of vision in
advanced cases
5
6. FIG 1.1
A healthy human eye
Jagat. R(2012) MEAJO. Pediatric Cataract
surgery. Vol. 19:1
FIG 1.2
Unilateral cataract in the right eye
6
7. CATARACT SURGERY
Eye
drops(containing an
anesthetic) that
dilate the pupils will
be administered
A tiny cut is made
in the cornea
through which a
probe is inserted
Probe breaks up
cloudy lens into
small pieces which
are sucked out
The artificial lens is
inserted through the
cut and sits in the
lens capsule. It
unfolds when in
position.
7
8. FIG 1.3
Removal and replacement of an infected lens with an artificial lens during cataract surgery
9. COMPLICATIONS OF CATARACT
SURGERY
Modern cataract surgery is safe in more than 95% of patients.
In a small number of cases, an intra-operative posterior
capsular rupture can lead to vitreous loss or a dropped
nucleus and can increase the risk of post-operative
complications.
CORNEAL EDEMA and CYSTOID MACULAR EDEMA are
common post-surgical complications that occur due to
persistent swelling in the cornea as seen in corneal edema or
in the retina as in cystoid macular edema. In both cases,
patients may notice blurred, foggy vision. The risk of either
occurring is around 1 in 100.
9
12. CORNEAL EDEMA
The endothelium continuously pumps fluid from the cornea
keeping it dry and clear as corneal clarity is essential for clear
vision.
Corneal edema is the hydration(swelling) of the corneal
stroma due to corneal endothelial injury/damage causing
decreased visual acuity.
It may occur naturally as in the genetic condition; Fuch’s
dystrophy or as a complication of cataract surgery.
12
13. CORNEAL EDEMA AS A
COMPLICATION OF CATARACT
SURGERY
Corneal edema often resolves within a few days or weeks post-
surgery.
If the cornea was not healthy prior to surgery, high intraocular
pressure(IOP) can cause the cornea to fail, and severe edema
can result.
Edema may persist for months after surgery. This may be the
case in Fuch’s dystrophy or extremely dense/difficult to remove
cataracts.
Some early designs of lenses implanted during surgery caused
injury to the endothelium. However, these implant designs are no
longer manufactured.
13
14. PATHOPHYSIOLOGY OF POST-
OPERATIVE CORNEAL EDEMA
Corneal tissue
must remain thin
and transparent for
clear vision
The corneal
endothelium
pumps fluid out of
the cornea keeping
it dry and clear
Cataract surgery with
or without pre-
existing Fuch’s
dystrophy can injure
the corneal
endothelium
Upon injury,
surviving cells
change shape and
grow larger to fill the
spaces left by the
destroyed cells
When a lot of cells
are damaged, the
cornea stroma will
be flooded by fluids
causing the
swelling (edema)
14
15. FIG 1.5
The hydrated corneal stroma causes reduced
visual performance and blurred vision as seen in
the image above
FIG1.6
Pseudophakic bullous keratopathy (PBK). Large multiple
bullae, such as depicted here, are associated with
moderate to severe pain and discomfort.
15
16. EPIDEMIOLOGY
The exact incidence rate for corneal edema is unknown. It is
however, estimated that 1% of patients undergoing cataract
surgery will develop this problem.
CORNEAL OEDEMA
AGE SEX RACE
Older
patients(
>50year
s) are
more
prone
No
known
associ
ation
No
known
associ
ation
16
17. EPIDEMIOLOGY cont’d
Despite an increase in the overall number of cataract
surgeries performed, cases of ABK and PBK have decreased.
The overall drop in the incidence of post-operative corneal
edema reflects the rapid development and improvement of
both intraocular lens design and cataract surgical technique.
17
18. TREATMENT/MANAGEMENT
Treatment of corneal edema is based on the exact cause.
There is no treatment to promote the healing of the destroyed
endothelial cells, though the extent of the edema can be
controlled.
A. HYPERTONIC DROPS AND OINTMENTS: Patients with
early/mild corneal edema may benefit from the use of
hypertonic/concentrated saline agents to reduce corneal
thickness.
Examples: 2% and 5% Hypertonic saline solution and
ointment.
Mode of action: These agents work by creating an osmotic
gradient via a tear film outside the cornea that pulls fluid from
the cornea.
18
19. TREATMENT cont’d
As evaporation from the tear film is minimal at night with the
eyes closed (therefore, the tears are less hypertonic), corneal
edema tends to be worse in the morning.
Use of hypertonic Nacl 5% ointment at night and/or a
hypertonic solution early in the morning limits this build-up of
edema.
A typical regimen is Hypertonic Nacl (Muro128®) 2% drops
used hourly in the affected eye until noon (4-5 times).
As the day progresses, evaporation from the tear film begins
to create relative hyper-tonicity of the tears, drawing fluid from
the cornea.
19
20. TREATMENT cont’d
Side effects: Nil or minor (e.g mild burning or irritation).
Rare severe side effects include; severe allergic reactions,
eye pain and changes in vision.
B. ANTI-INFLAMMATORY AND INTRA-OCULAR
PRESSURE(IOP)-LOWERING AGENTS: Treatment of
edema in eyes with borderline endothelial function should
be focused on ocular inflammation and elevated
intraocular pressure if present.
The IOP inside the eye may become elevated due to
inflammation in the eye following surgery causing the
drainage angle inside the eye to be blocked.
If the pressure is 25mmHg - 35mmHg, the patient should
begin IOP-lowering drops.
20
21. TREATMENT cont’d
Examples of anti-inflammatory agents: Ketorolac 0.4% qid,
Diclofenac 0.1% (Voltaren®) t.i.d and Corticosteroids such as
Prednisolone acetate 1% solution 2-4 times daily used for not
more than 10 days.
Mode of action: NSAIDs act by blocking the cyclo-oxygenase
enzymes, COX-1 and COX-2(mediates production of
prostaglandins that contribute to the inflammatory response and
ocular disease). Inhibition of COX-2 determines the clinical
efficacy of an ophthalmic NSAID.
Side effects: Mild effects include; Burning and stinging, itchy
eyes, dizziness, headache. Serious effects include; Eye pain,
eye discharge and blurred vision.
21
22. TREATMENT cont’d
Examples of IOP-lowering drugs: Selective alpha 2-adrenergic
agonists such as Brimonidine 0.2% (Alphagan®) t.d.s or beta-
adrenergic blockers such as Timolol 0.25% and 0.5% b.d
ophthalmic preparations.
Mode of action: These drugs lower IOP by reducing the
production of aqueous humor and facilitating it’s outflow.
Side effects: Timolol may cause eye irritation, double vision,
drowsiness and in severe cases, fainting, breathing difficulties
and sudden weight gain.
Brimonidine may cause blurred vision, red/swollen eyelids,
sore throat and in sever cases, blind spots, dizziness and
rash.
22
23. TREATMENT cont’d
C. SURGICAL PROCEDURES: These include; Anterior
Stromal Puncture, Bandage contact lenses and Corneal
Transplant.
1) Anterior Stromal Puncture: Patients who have poor visual
potential and severe pain can benefit from this safe, simple
cost-effective procedure.
Small superficial punctures are placed in the affected area
of the cornea with depths just at the Bowman’s layer.
A bandage contact lens is the applied as an adjunct and left
for 7-14 days to hold the healing epithelium in place as it
grows back over the cornea.
23
24. TREATMENT cont’d
2) Bandage contact lenses: These are soft lenses useful for the
temporary relief of pain and discomfort due to bullous
keratopathy.
They must not be too tight as this may worsen the edema
especially when used at night.
They can increase the risk of infections. Therefore, antibiotics
are prescribed for corneal edema patients using Bandage
lenses.
A broad-spectrum antibiotic such as Polymyxin-B ophthalmic
drop/ointment used 2-4 times a day for 7-10 days is
recommended.
Bandage contact lens
24
25. TREATMENT cont’d
3) Corneal Transplant: Ultimately, if vision is substantially impaired,
the surgeon can transplant the entire cornea.
Corneal transplant, when paired with glasses or contact lenses,
often restores vision to a significant degree.
Only the endothelial layer of cells may be replaced in cases of
advanced edema resulting in fewer side effects than a full
transplant.
The procedures used are called Deep Lamellar Endothelial
Keratoplasty or Descemet’s Stripping Endothelial Keratoplasty.
25
26. CONCLUSION
Surgical removal of cataract is a routine and safe procedure.
Patients are advised to report any complications occurring
post-surgery to their physician(s). Corneal edema can be
effectively resolved with the restoration of vision to a
significant degree.
26
27. REFERENCES
Alpa S. Patel MD(2014). Cataract. American Academy Of Ophthalmology.
Available from eyewiki.aao.org/Cataract
Ocampo J, etal(2014). Senile Cataract. eMedicine [MedScape]. Available from
emedicine.medscape.com/article/1210914-overview
Christian Nordqvist(2014). What are Cataracts? What causes Cataracts?
Medical News Today. Available from
medicalnewstoday.com/articles/157510.php
Elsie C, Omar A(2010). Complications of Cataract Surgery. Clinical and
Experimental Optometry. DOI: 10.1111/j.1444-0938.2010.00516.x
University of Washington Medical Center(2015). Corneal Edema. Available from
uwmedicine.org/health-library/Pages/corneal-edema.aspx
Brunton L, Chabner B, Knollman B(2010). Corneal endothelium. Goodman &
Gilman’s The Pharmacological Basis of THERAPEUTICS (12th ed). Mc Graw Hill
Medical, California: pp1774-1775
Taravella M, etal(2014). Post-Operative-Corneal-Edema. eMedicine
[Medscape]. Available from emedicine.medscape.com/article/1193218-overview
27
28. Drugs.com [ Micromedex® , Cerner Multum™ , etal(2015) ]. Sodium chloride
drops: Indications, Side Effects, Warnings. Available from drugs.com/cdi/sodium-
chloride-drops.html
The American Society of Health-System Pharmacists(2011). Diclofenac
Ophthalmic. US. National Library of Medicine[MedlinePlus]. Available from
nlm.nih.gov/medlineplus/druginfo/meds/a606003.html
The American Society of Health-System Pharmacists(2010). Timolol Ophthalmic.
US. National Library of Medicine[MedlinePlus]. Available from
nlm.nih.gov/medlineplus/druginfo/meds/a682043.html
The American Society of Health-System Pharmacists(2011). Brimonidine
Ophthalmic. US. National Library of Medicine[MedlinePlus]. Available from
nlm.nih.gov/medlineplus/druginfo/meds/a601232.html
Zauberman N, etal(2014). Anterior Stromal Puncture for the Treatment of
Recurrent Corneal Erosion Syndrome: Patient Clinical Features and Outcomes.
American Journal of Ophthalmology Vol. 157, Issue 2: pp273-279
Fan M, etal(2014). Anterior Stromal Puncture. American Academy of
Ophthalmologists. Available from eyewiki.aao.org/Anterior_Stromal_Puncture
Taravella M, etal(2014). Post-Operative-Corneal-Edema. eMedicine [Medscape].
Available from emedicine.medscape.com/article/1193218-treatment
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