Cataract is the commonest cause of blindness and visual impairment in India. It affects a significant number of elderly people’s quality life and economic productivity. This age related condition usually presents with gradual dimness of vision in both eyes. In the earlier stages, patients may experience glare, especially while driving at night. There may be monocular diplopia or polyopia, reduced contrast sensitivity and altered colour perception. Over a period of time, the cataracts can advance and can cause total blindness.
Very rarely, children can also have cataract. These children are born with this disorder or develop it at a very early age. The definitive treatment is always surgery with a very favourable risk reward ratio. In fact, cataract surgery is one of the most cost-effective public health interventions worldwide.
Ministry of Health and Family Welfare, Government of India has issued the Standard Treatment Guidelines for Cataract. Following are the major recommendations:
A cataract is any opacity of the crystalline lens or its capsule leading to degradation of its optical quality, thereby causing decreased quality of vision.
II. INCIDENCE OF THE CONDITION IN OUR COUNTRY
In India cataract has been reported to be responsible for 50-80% of the bilaterally blind in the country .Data from a population based longitudinal study of randomly selected communities in Central India have for the first time provided direct estimates of age specific incidence of blindness from cataract. It estimated that 3.8 million persons become blind from cataract each year in India. The absolute number of cataract blind which was 7.75 million in 2001 is likely to reach 8.25 million in 2020 due to a substantial increase in the population above 50 years in India over this period.
The 60+ population which stood at 56 million in 1991 will double by 2016.This increase in population means that the population ‘at-risk’ of blinding cataract will also increase tremendously. The economic loss due to blindness and visual disability from cataract is enormous. Cataract blind people are unable to work and thus due to lack of productivity, the economic impact is a staggering 4.5 million rupees per year of every million population.
Cataract in children, although rare, can still happen. The prevalence of blindness among children in different regions varies from 0.2/1000 children to over 1.5/1000 children with a global figure estimated at 0.7/1000. In India this figure is approximately 1 per 1000 children. The proportion of blindness in children due to cataract varies considerably between regions from 10%-30%. Children who are blind have to overcome a lifetime of emotional, social and economic difficulties which affect the child, the family and society.
Timely recognition and intervention can eliminate blind-years due to childhood cataract, as the condition is treatable.
III. DIFFERENTIAL DIAGNOSIS
Cataract presents as a white reflex in the central part of the pupil. There are some other common conditions of the eye that show white reflex in the pupillary area and mimic cataract.
Old Retinal Detachment
Intra ocular tumour
Persistent hyperplastic primary vitreous
IV. PREVENTION AND COUNSELING
Cataract is mostly age related and there is no effective way of preventing this condition. However there are certain secondary types of cataract which can be prevented.
Traumatic cataract is very common in India especially among younger adults and children. Education about occupational safety and avoiding dangerous games (e.g. Bow and arrow) can reduce incidence of traumatic cataract.
Drugs, commonly corticosteroids (either local or systemic) can produce cataract after prolonged use. This can be prevented by judicious application of the medicine.
Heredity plays a role in some families. Multiple children in a family are either born with cataract or develop cataract at a very young age. Genetic counseling has some role in prevention. Early eye check up for all the children in those families can be advocated.
Maternal infections during pregnancy, most commonly rubella, can give rise to congenital cataract. This can be prevented by immunizing the target age group of women.
Smoking is known to be associated with nuclear cataract and hence preventing smoking is thought to be beneficial.
Ultraviolet-B radiation has been associated with lens opacities and hence protecting eyes from sun has some role in prevention.
Diabetes mellitus has a higher risk for cataract formation, and behavior modification to reduce the risk of developing type 2diabetes may be effective.
V. OPTIMAL DIAGNOSTIC CRITERIA, INVESTIGATIONS, TREATMENT & REFERRAL CRITERIA
*Situation 1: At Secondary Hospital/ Non-Metro situation: Optimal Standards of Treatment in Situations where technology and resources are limited
a) Clinical Diagnosis:
Cataracts is an extremely common occurrence in the elderly. However, the key is to determine whether the cataract is the cause of functional disability for an individual. Careful history taking is important for assessing the quality of the visual impairment due to this disability. Occupational and functional needs of the patients should be taken into consideration before planning for surgical intervention.
History should also include ocular and systemic medications currently and previously used.
Medical history about systemic diseases is important. Patients should be asked about any allergy to any food or medicine.
i. Presenting Visual acuity with and without present correction (if spectacle is available, the power of the present correction should be recorded) is determined
In advanced and mature cataract, perception and projection of light should be tested in all the four quadrants to rule out gross retinal problems.
ii. Measurement of best-corrected visual acuity (with refraction when indicated).
iii. External examination (lids, lashes, lacrimal apparatus, orbit).
Pressure should be applied over the sac to look for any regurgitation. If regurgitation is positive or dacryocystitis is suspected syringing of naso-lacrimal duct should be carried out. If duct is not free, with mucus or purulent discharge, dacryocystectomy or dacryocystorhinostomy is done and cataract surgery is done after one month.
iv. Examination of ocular alignment and motility.
v. Assessment of pupillary shape, size and reaction: This is a very important step and should be done very carefully, since it will help in determining the prognosis.
vi. Slit-lamp biomicroscopy of the anterior segment : Special emphasis should be made to examine the corneal endothelium for any guttata, pupil for pseudoexfoliation and the lens for any preoperative compromises on stability.
vii. Dilated Examination of the lens opacity may reveal the extent of visual impairment. For example, opacity in the visual axis may cause more functional visual deficit than a peripheral cataract posterior sub-capsular opacity may cause more symptoms of glare than a nuclear cataract. It helps in grading nuclear sclerosis and reveals any subluxation. Measuring amount of maximal dilation helps in planning the surgery.
viii. Dilated examination of the fundus including, optic disc, macula and vitreous. If clarity of media allows then the peripheral retina should be examined. This helps in planning the prognosis of the surgical intervention.
ix. Indirect ophthalmoscopy is indicated for known myopes, eyes with past history of trauma or retinal detachment in other eye.
i. Measurement of intraocular pressure (preferably by Applanation tonometry)
ii. Gonioscopy is not done as a routine. It can be performed if anterior chamber appears shallow, IOP is raised, presence of any sign that can be related to secondary glaucoma (e.g. pseudoexfoliation) or known cases of glaucoma.
iii. Keratometry and A scan biometry: It should be performed in both eyes. It should be repeated if needed for unusual powers of IOL. Appropriate formula should be used according to cases. In case of scarred cornea and irregular surface of cornea, the K reading will not be possible. In this case the other eye should be taken into consideration.
iv. Ultrasonogram of the posterior segment is indicated in traumatic cataracts, complicated cataracts and unilateral mature cataracts.
v. Blood pressure
vi. Screening for diabetes mellitus
vii. Physician fitness is mandatory for cardiac patients and those with advanced systemic problems.
viii. Patients who require general anesthesia need to undergo preanasthetic check up.
Patients with early cataract and all stages of nuclear cataracts may sometimes benefit by spectacles. If they do benefit, then subsequent follow ups can be planned to determine the timing of surgery, if required.
Management of a visually significant cataract is primarily surgical.
Indications for Surgery
An individual who is unable to carry out his/her desired activities due to dimness of vision for which cataract surgery is likely to restore the visual function is the prime indication for surgery. The other reasons for a cataract removal include the following:
i. Clinically significant anisometropia in the presence of a cataract where cataract surgery is likely to facilitate binocularity.
ii. Conditions in which the lens opacity is dense enough to interfere with evaluation and management of posterior segment conditions.
iii. Lens induced ocular inflammation
iv. Lens induced glaucoma
Prognosis of surgery should be clearly explained to the patient in an understandable language.
Contra-indications for surgery:
i) Patient not convinced about surgery
ii) Patient has satisfactory functional vision either with or without visual aids
iii) Cataract surgery is unlikely to improve vision
iv) Patient is medically unfit
Cataract surgery may be performed using a variety of anesthesia techniques that include general and local (regional) anesthesia (e.g., retrobulbar, peribulbar, periocular, sub-Tenons injection, topical, and intracameral). Local (regional) anesthesia is generally used, with or without sedation/analgesia. Traditionally, a retrobulbar or peribulbar anesthesia is used for most of the extracapsualr cataract surgeries. Topical anesthesia can be used for patients undergoing clear corneal phacoemulsification. General anesthesia may be utilized if needed for children and patients with medical, psychosocial, or surgical indications. The planned mode of anesthesia should be decided after interaction between patient and the doctor. The process should be discussed with the patient so that he/she will know what to expect in terms of pain, discomfort, consciousness level, visual experiences, and complications.
Greatest concern of an ophthalmologist after successful surgery is the endophthalmitis because of its serious consequences. Prevention remains the best measure to avoid it. Risk for endophthalmitis can be lessened by reducing the number of microorganisms on the ocular surface.
Prophylactic strategies that are commonly practiced include using topical antibiotic eye drops before surgery, applying 5% povidone iodine to the conjunctival cul de sac, preparing the periocular skin with 10% povidone iodine, careful sterile draping of the eyelid margins and eyelashes, and applying topical antibiotic eye drops after surgery.
Taking care of personal hygiene of the patient is very important. A thorough face washes before surgery is recommended. A surgeon should stick to strict aseptic techniques of surgeries.
Wound construction and closure should be meticulous. The surgery should end with a water tight incision and the surgeon should not hesitate to put sutures for security.
Surgical Techniques The preferred method to remove a cataract is extracapsular extraction by either of the following techniques:
a. Manual small incision cataract surgery
b. Conventional extracapsular cataract extraction.
Visual results can be improved in all these types of surgeries by adhering to these common guidelines.
A well planned incision that minimizes surgically-induced astigmatism.
Safe and secure incision.
Ensuring minimal loss of the corneal endothelial cells
An appropriate posterior chamber IOL placed in the capsular bag.
Avoiding trauma to iris, and other ocular tissues.
Incision location, size, and design may depend on several factors, including the patient’s orbital anatomy, the type of IOL to be implanted, the role of the incision in astigmatism management, and surgeon preference and experience.
Manual small incision cataract surgery: This surgery is known to be extremely cost effective and visual improvements are comparable to other technique like phacoemulsification. This can be performed through superior incisions or temporal incisions. While superior incisions would be relatively safer with regard to the occurrence of endophthalmitis (since the incision is protected by the lids), it causes a higher astimagtism than the temporal incision. If temporal incisions have to be performed because of excessive preoperative astigmatism, care should be taken to fashion a longer internal corneal valve and the tunnel may be secured with a couple of nylon sutures. While any type of anterior capsular opening techniques can be used alongside this procedure, capsulorrhexis is preferred for better centration of the intraocular lenses and reduced inflammation. The cataractous lens can be taken out by irrigating vectis or by viscoexpression. Rigid or foldable lenses can be used as per the needs of the individual patient.
Extra capsular cataract surgery:
This surgery can be performed on hard cataracts, shallow anterior chambers or a bulky nucleus which may be difficult to express through a smaller incision. The decision to perform this surgery has to be decided upon by the needs of the patients along with the comfort level of the surgeon. The main drawback of this surgery is the increased need for postoperative follow ups which may be necessitated due to problems associated with sutures. Astigmatism can also be a significant issue which may warrant a suture removal, in order to optimize good uncorrected visual acuity.
Phacoemulsification: This surgery can be performed on early to intermediate level of hardness of cataract and produces rapid visual recovery. It also eliminates the risk of regional anasthesia since it may be performed topically. There is a learning curve for surgeons and once it is mastered, it can be employed in a significant number of cases. Harder cataracts may require an experienced surgeon and a machine with good fluidics.
However, this procedure is expensive and sometimes may be difficult to perform in certain types of cataracts.
In all these types of surgeries, there are chances of intraoperative complications. The most common causes are posterior capsular rupture and zonular dialysis. If this happens, the management of vitreous loss is crucial and should be managed by automated vitrectomy.
Intraocular Lenses Posterior chamber IOLs (PC IOL) are the best choice unless contra-indicated. Other less commonly used lenses are Anterior Chamber and Scleral Fixated IOLs.
There is a wide range of PC IOLs with various value added optical and non optical characteristics. The most common materials used are polymethyl methacrylate (PMMA) and acrylic lenses. Even though they have comparable visual acuity outcomes, the rates of posterior capsular opacification (PCO) is lower in acrylic than PMMA. In patients, where there is more chance of posterior capsular opacification,as in children or diabetics or others, acrylic lenses may be preferred. Acrylic lenses can be hydrophobic or hydrophilic. Another parameter which has been thought to influence PCO occurrence is the design of the intraocular lenses. Square edged lenses are known to cause a lower incidence of PCO.
The ophthalmologist can choose any of these PCIOLs according to clinical indications, patient’s visual need and affordability.
Anterior chamber lenses if used at all, should preferably be single-piece flexible open-loop. Effective and safe use of an anterior chamber lens depends on appropriate sizing. Anterior chamber IOLs are used most often when there is inadequate capsule support for a posterior chamber IOL. Placement of an anterior chamber lens requires a peripheral iridectomy and proper anterior vitrectomy.
The surgeon should have access to a variety of lens styles to select an appropriate IOL for an individual patient. Variations in the preoperative state of the eye, the surgical technique, patient expectation, and surgeon experience and preference affect the decision.
Post Operative Medication:
i) Topical corticosteroid in a tapered fashion for 4 to 6 weeks.
ii) Topical broad spectrum antibiotics for two weeks.
iii) Cycloplegic drops, NSAID and anti glaucoma medications according to ophthalmologist’s clinical decision.
Outcomes of cataract surgeries should be carefully monitored and results used for improvement of service. Presenting visual acuity, rather than best corrected visual acuity should be taken as the standard for assessing visual success. Complications of Cataract Surgery should be carefully documented clearly explained to the patient in their own language and appropriate care given.
Standard Operating procedure
a. In Patient
i. Patients coming from a long distance
ii. Traumatic cataracts
iii. Cataracts with intraoperative complications:
iv. Pediatric patients requiring anesthesia.
v. Mono ocular patients.
b. Out Patient
Pre operative investigations
C. Day Care
Cataract surgery is ideally done as a day care procedure.
d) Referral criteria:
Cases needing specialized investigations before surgery (Specular microscopy)
Cases not manageable by the facilities available
Seeking second opinion
Complications needing specialized intervention (e.g. posterior vitrectomy)
Detection of posterior segment disorder after cataract removal
*Situation 2: At Super Specialty Facility in Metro location where higher-end technology is available
a) Clinical Diagnosis: Same as situation 1
b) Investigations: Same as situation 1. Some additional investigations help in explaining prognosis and planning the surgery.
b. Corneal topography, corneal pachymetry and , specular microscopy for associated corneal disease. Specular microscopy is helpful for planning surgery in hard cataracts and in patients with suspected compromised corneas.
c. Fluorescein angiography is helpful in vascular retinopathies and maculopathies if clarity of media permits.
d. An automated field analyzer evaluation may be helpful in preoperative diagnosis of co-existing glaucoma.
e. Conjunctival swab culture for suspected infections
f. Additional investigations for paediatric cataracts according to systemic conditions.
c) Treatment: Same as situation 1. Difficult cases should get individualized attention according to the merit of the case. Correction of pre-existing astigmatism can be taken either with selection of the incision sites, using toric intraocular lenses or by limbal relaxing incision. Patients desiring multifocal lenses should be counseled appropriately and then taken for surgery. Paediatric cataracts should be appropriately managed by trained surgeons.
Standard Operating procedure
a. In Patient
Patients preferring hospital stay for surgery because of distance and better care
Children undergoing cataract surgery
Patients with post operative complications that need institutional care
g. Out Patient
Pre operative investigations
h. Day Care
Ideal for cataract surgery.
d) Referral criteria: Does not apply
VI. WHO DOES WHAT? AND TIMELINES
Patient History is taken and a Clinical Examination performed
Documenting the medical record
Plan treatment guidelines and counsel patients
Advise and Perform surgery. Explain and assure patients if complications occur.
Referral in needed.
Monitoring the infection control process
Monitoring outcome and share the results with the team
b. Nurse / Technician
Receive the patients and assist in clinical examination
Prepare the patients for surgery
Counseling whenever necessary
To monitor the patients who are admitted regarding application of eye drops and ensure compliance
To maintain separate inpatient and outpatient record
To maintain lab reports
Explain discharge advice to patients
|Situation||HUMAN RESOURCES||INVESTIGATIONS||DRUGS AND CONSUMABLES||EQUIPMENT|
5) OT Nurse
6) Ward Nurse – 1
7) Counsellor – 1
3)Sac syringing (if
6) USG B scan
lenses in various
8)Dyes to stain
9) Needles and
4)Slit lamp –
6)+90 D lens
+20 D lens
19) Nd: YAG laser
5) OT Nurse
6) Ward Nurse –
7) Counsellor – 1
3)Sac syringing (if
6)USG B- Scan
In addition, a specular
and an automated field
analyzer and equipments
for documenting fundus
Guideline of Ministry of Health & Family Welfare Govt. of India.
Group Head Coordinator of Development Team
Dr. Venkatesh Prajna Chief- Dept of Medical Education,
Aravind Eye Hospitals, Madurai