Cataract is characterized by visual impairment due to opacification of the crystalline lens.
A general practitioner should recognize the symptoms of cataract, examine visual acuity and, if cataract is suspected, refer the patient to an ophthalmologist for further investigations. The referral should contain information on the patients general condition, chronic illnesses and medication.
Cataract should be operated on when the harm caused by impaired vision is significant. Justification for surgery is always individually assessed.
Risk factors
Risk factors predisposing to the development of cataract include e.g.
advanced age
diabetes
high body mass index, excessive consumption of alcohol, smoking
glucocorticoids (systemic or inhaled preparations as well as topically administered eye drops; the risk is individual and is not dose-dependent)
chemical or physical eye injuries, eye operations, radiation exposure (sunlight, ionizing radiation)
Chronic uveitis
Metabolic diseases and some rare hereditary syndromes.
Cataract can also occur in children. The cause may be
congenital
a sharp or blunt blow to the eye.
Symptoms
Gradual impairment of vision that cannot be corrected by glasses
Cataract is often bilateral.
Altered refractive power of the crystalline lens
Glare
Impaired contrast sensitivity
Monocular double vision
Changes in colour vision
Investigations
The distance visual acuity is determined both without glasses and with the patient's current glasses for distance vision.
On examination with a penlight the pupil may be pale, greyish, or greenish brown (pictures 12).
The pupil reacts to light.
At ophthalmoscopy the red reflex is dull, extinct or shady (picture 3).
The visibility of the ocular fundi is poor or absent.
The intraocular pressure is normal (a mature, swelling cataract may, however, cause an acute increase in intraocular pressure.)
Assessing the need for treatment
Indications for surgical treatment are considered individually.
The health authorities may set criteria for elective cataract surgery. E.g. the following rules may be applied when considering the indications for surgery:
visual acuity in the better eye using the best glass correction is 0.5 or worse
if the visual acuity in the better eye is better than 0.5, the worse eye should have visual acuity of 0.3 or worse (using the best glass correction) for the surgery to be indicated.
More loose criteria may, however, be applied and surgery may be indicated if
posterior subcapsular cataract significantly impairs the activities of daily living
after the operation on the first eye the patient is left with handicapping anisometropia (over 2 dioptres)
cataract hampers the follow-up of another eye disease (e.g. diabetic retinopathy or glaucoma).
Surgery should, however, not be performed even if the criteria were fulfilled if
the patient does not want it
glasses or assistive devices are sufficient for the patient's needs
no benefit is to be expected from the operation considering the patient's comorbidities and other factors affecting the quality of life or
the surgery cannot be safely arranged due to a systemic disease or another ophthalmopathy.
Referral to an ophthalmologist is urgent if all the following conditions are fulfilled:
the anterior chamber is lower than in the other eye, or the intraocular pressure is markedly increased (> 30 mmHg).
In other cases a normal referral is made. The patient's general condition, long-term illnesses and medication are reported on the referral. It is also possible to ask about the patient's willingness to surgery already in advance.
If the patient's coping with the daily activities significantly deteriorates due to poor visual acuity while he/she already is on the waiting list for specialist assessment, the call to specialized care should be hurried on if necessary.
A driving prohibition should be verbally issued (country-specific variation may apply) to the patient, if his/her visual acuity does not fulfill relevant criteria.
The first choice is always a monofocal intraocular lens, but in special cases, a multifocal or astigmatism correction toric intraocular lenses can be used.
The patient is operable if he/she is able to lie supine (without e.g. significant dyspnoea).
Tremor of the head or restlessness may be an indication for general anaesthesia.
After the operation
If sufficient assistance in postoperative care is not otherwise arranged for, the primary health care services should take responsibility for it.
Topical treatment usually consists of broad-spectrum antimicrobial eye drops administered 4-5 times daily for 2-4 postoperative weeks. Topical glucocorticoid drops are recommended for 4 weeks to reduce intraocular inflammation and ocular irritation. The use of topical NSAID eye drops may reduce the risk of postoperative cystoid macular oedema, but its efficacy in treating post-operative swelling is uncertain.
Applying the drops can be made easier with an eye drop delivery device available in pharmacies.
If the patient had preoperatively used medication to decrease intraocular pressure, this is usually continued until the follow-up visit, at which the need of the medication is reassessed.
Refer the patient to an ophthalmologist if there is a cumbersome feeling of a foreign body (caused by the sutures; nowadays sutures are used only rarely).
Refer the patient to a hospital immediately if the visual acuity has been impaired rapidly or if the patient has pain in the eye (the patient may have endophthalmitis or high intraocular pressure).
Postoperative follow-up examination by an ophthalmologist is medically justified because the occurrence of complications in individual patients cannot be predicted. The follow-up examination is carried out about one month after the operation in order to exclude postoperative complications. The examination includes the inspection of the surgical scars, cornea, anterior chamber, intraocular lens and ocular fundus, as well as measurement of intraocular pressure.
The refractive power of the eye is usually changed by cataract surgery, and this may affect the need of spectacles as well as their strength. Postoperative spectacle prescription is recommended to be given after about one month.
Painless gradual impairment of visual acuity during the first weeks or months may be due to corneal clouding or cystic macular oedema of the ocular fundus. Later, it is usually caused by so-called after-cataract, i.e. the opacification of the lens capsule. The red reflex is blurred. The condition is treated on an outpatient basis by making a hole in the lens capsule with YAG laser.
References
Wingert AM, Liu SH, Lin JC, et al. Non-steroidal anti-inflammatory agents for treating cystoid macular edema following cataract surgery. Cochrane Database Syst Rev 2022;12(12):CD004239. [PubMed]
Singh R, Barker L, Chen SI, et al. Surgical interventions for bilateral congenital cataract in children aged two years and under. Cochrane Database Syst Rev 2022;9(9):CD003171. [PubMed]
Maedel S, Evans JR, Harrer-Seely A, et al. Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery. Cochrane Database Syst Rev 2021;8(8):CD012516. [PubMed]
Day AC, Donachie PH, Sparrow JM, et al. The Royal College of Ophthalmologists' National Ophthalmology Database study of cataract surgery: report 1, visual outcomes and complications. Eye (Lond) 2015;29(4):552-60. [PubMed]
Endophthalmitis Study Group, European Society of Cataract & Refractive Surgeons. Prophylaxis of postoperative endophthalmitis following cataract surgery: results of the ESCRS multicenter study and identification of risk factors. J Cataract Refract Surg 2007;33(6):978-88. [PubMed]