Retinal screenings

Overview of Treatment

Retinal screening is a diagnostic procedure used to assess the health status of the retina, primarily through the use of specialized equipment to observe retinal blood vessels, neural layers, and macular structures. The purpose of this examination is to detect early potential lesions such as diabetic retinopathy, glaucoma, and age-related macular degeneration, thereby enabling the formulation of preventive treatment plans. Unlike therapeutic medical interventions, retinal screening falls within preventive medicine, effectively reducing the risk of permanent vision loss.

Using high-resolution imaging technology, physicians can promptly identify signs such as microaneurysms, retinal hemorrhages, or neural cell atrophy. This procedure is typically a necessary component of regular follow-up for patients with chronic diseases, especially among diabetics, where it can reduce the risk of vision impairment by over 60%. Regular screening allows for early intervention, preventing progression to irreversible stages.

Types and Mechanisms of Treatment

Retinal screening encompasses various techniques:

• Fundus examination: direct observation of retinal blood vessels and neural layers by the physician
• Optical Coherence Tomography (OCT): laser-based measurement of retinal layer thickness
• Choroidal angiography: injection of contrast dye to track blood flow

These techniques collectively generate three-dimensional images, aiding physicians in accurately assessing the severity of lesions.

Mechanistically, OCT utilizes near-infrared light to penetrate tissue, allowing differentiation of micrometer-scale structural changes, while fluorescein angiography reveals vascular leakage and blockages. Integrating these data can predict risks such as macular edema or retinal detachment, guiding treatment strategies like laser therapy or anti-VEGF injections.

Indications

Primarily suitable for high-risk groups such as:

• Patients with a history of diabetes exceeding 5 years
• Patients with hypertension or hyperlipidemia
• Individuals with a family history of retinal detachment
• Patients on long-term steroid therapy

These groups have a 3-5 times higher risk of retinal lesions due to fragile microvasculature or abnormal blood circulation.

Additionally, for those over 40, comprehensive screening is recommended every 2 years, and annually for those over 60. Patients who have undergone cataract surgery need to re-establish baseline measurements to compare pre- and post-operative changes.

Usage and Dosage

The examination process involves three stages:

1. Pupil dilation: using cycloplegic agents (such as mydriatics) to enlarge the pupils
2. Image capture: digital photography or scanning for 15-20 minutes
3. Report analysis: interpretation of abnormal indicators by specialist physicians

The non-invasive design makes the procedure painless and safe.

Screening frequency is adjusted based on risk levels:

• Early-stage diabetic patients: once annually
• Patients with mild lesions: once every 6 months
• High-risk glaucoma groups: combined with intraocular pressure testing every 3-6 months

Patients with mobility issues can opt for home-based simplified screening kits, though their accuracy is only 70-80% of medical-grade standards.

Benefits and Advantages

Main benefits include:

• Early detection of reversible lesions
• Reducing the risk of 90% of vision loss
• Shortening decision-making time for treatment

A 2023 study by the Taiwan Diabetes Association shows that regular screening allows laser treatment to be initiated on average 14 months earlier, increasing success rates by 35%.

Advantages are:

• Non-invasive examination
• Ability to monitor disease progression
• High correlation with other tests such as visual field testing

Results can serve as key references for surgical planning, such as laser targeting for macular edema treatment.

Risks and Side Effects

Main risks include:

• Photophobia after pupil dilation (lasting 4-6 hours)
• 0.3% chance of allergic reaction to dilation agents
• Elevated intraocular pressure in susceptible individuals potentially triggering acute glaucoma

Rare cases may experience temporary blurred vision, usually recovering within 24 hours.

Serious complications are extremely rare, including allergic reactions to contrast agents (incidence 0.02%) or thermal damage to retinal tissue from laser (less than 0.01%). Prior to contrast injection, patients should confirm no allergy to iodine or iodine-containing contrast media.

Precautions and Contraindications

Contraindications include:

• Severe glaucoma attack
• Heart or kidney failure preventing contrast metabolism
• Severe cataracts affecting vision

Pregnant women should evaluate fetal risks before contrast injection; non-invasive OCT is recommended as an alternative.

Before the examination, note:

• Avoid caffeine drinks 2 hours prior
• Bring sunglasses due to photophobia after dilation
• Diabetic patients should control blood sugar below 150 mg/dL

Patients with special conditions such as severe dry eye should inform medical staff in advance.

Interactions with Other Treatments

Examination results directly influence treatment choices:

• Microvascular leakage → laser photocoagulation
• Macular edema → anti-VEGF injections
• Optic nerve compression → intraocular pressure-lowering medications for glaucoma

Screening data can be cross-verified with electroretinogram (ERG) results to improve diagnostic accuracy.

Relation to surgical treatments: Pre-cataract surgery screening can evaluate the feasibility of intraocular lens implantation; post-operative follow-up can assess retinal detachment risk. Patients receiving anti-VEGF therapy during chemotherapy should have retinal structure monitored every 3 months.

Effectiveness and Evidence

Large studies show that regular screening reduces the blindness rate of diabetic retinopathy by 58%. The American Academy of Ophthalmology (AAO) recommends annual screening for type 2 diabetics from diagnosis, reducing severe retinal disease risk by 73%.

The 2022 Lancet study indicates that combining OCT with adaptive optics technology can detect tiny lesions as small as 0.1mm with an accuracy of 97.6%. These data provide an objective basis for personalized treatment plans.

Alternatives

Non-medical grade alternatives:

• Home vision test cards (accuracy 60-70%)
• Automated retinal cameras (requiring remote physician interpretation)

but cannot replace real-time professional diagnosis.

Medical alternative procedures:

• Electrophysiological tests (ERG/EOG)
• Ultrasound biomicroscopy

but these methods have lower sensitivity for microvascular lesions and are usually used as supplementary examinations.

 

Frequently Asked Questions

What preparations are needed before the examination? Is fasting or medication cessation required?

Generally, no fasting is required before retinal screening, but if pupil dilation is involved, it is recommended to avoid taking medications that may affect pupil constriction (such as certain antihistamines) 4 hours prior. Patients with diabetes or high myopia should inform medical staff in advance for adjustments.

Will the examination cause discomfort or pain in the eyes?

Typically, retinal screening is painless, but pupil dilation may cause temporary photophobia or blurred vision lasting 4-6 hours. Using fundus cameras or OCT only requires keeping the head steady and avoiding rapid eye movements, with no pain involved.

What should be done if abnormal symptoms occur after the examination?

If severe photophobia or blurred vision persists beyond 8 hours after dilation, or if eye pain or headache occurs, seek medical attention immediately. It is recommended to wear UV-protective sunglasses when going out and avoid driving alone, as vision may not be fully recovered.

How often should screening be performed at different ages?

Under 40 without a family history should be screened every 2-3 years; over 40 or diabetics are advised to have annual checks; those with high myopia (over 600 degrees) should follow up every 6-12 months. High-risk groups such as premature infants with retinopathy of prematurity should follow personalized schedules as advised by their physicians.

What follow-up steps are involved if abnormal lesions are detected?

If retinal tears or macular lesions are found, laser photocoagulation or cryotherapy may be recommended; severe diabetic retinopathy may require anti-VEGF injections or vitrectomy. All treatment plans are tailored based on lesion severity and overall health status.