Diabetic Retinopathy Exam: Key Questions

• Direct Ophthalmoscopy, Diabetic Retinopathy & Thyroid Eye Disease are the subject of this lecture.

Direct Ophthalmoscopy

• It is a standard instrument for clinical examination of the ocular fundus.
• It has a 15x magnification.
  • Myopia results in a larger image.
  • Hyperopia results in a smaller image.
• The field of view from the instrument is measured at 6.5 degrees or 2DD in an emmetropic eye.

Apertures for Direct Ophthalmoscopy

• Micro-spot aperture allows quick entry into small, undilated pupils.
• Small aperture provide an excellent view of the fundus if the pupil is undilated.
• Large Aperture is standard for a dilated pupil and general eye exam.
• Fixation Aperture has graduated cross-hairs for fixation measurement or lesion location.
• Cobalt filter is used with fluorescein dye to view small lesions, abrasions, and foreign objects on the cornea.
• Slit is used to determine the levels of lesions and tumors.
• Red-free filter excludes red rays from examination for easy identification of veins, arteries, and nerve fibers.

Hand and Scope Position

• The ophthalmoscope is held in the right hand when examining a patient's right eye.
  • The index finger is placed on the lens wheel.
• The ophthalmoscope is held in the left hand when examining a patient's left eye.

Patient and Examiner Position

• The patient should sit forward at eye level or stand at shoulder level.
• Both eyes should be open, fixated at a distance target.
• The examiner stands to the patient's right side to view the right eye.
  • The examiner should be approximately 25cm (10") from the eye.
• The examiner should stabilize themselves.
• Assess external structures like eyelids, lashes, conjunctiva, and cornea.
• The examiner should see the red reflex of the retina.
  • Move closer to the patient to view the retina after this.

"Dialing" and Focus

• Focus should be adjusted while moving closer to the patient.
• With the index or middle finger slightly extended and bent, push up on the lens wheel using the right index finger (down with the left).
  • This will move the focal point toward the retina and optic nerve.
• Lenses should not be changed if the existing image is clear.
  • Only change the lens if the image gets out of focus or blurry.
• Reduce plus or add minus lenses in the instrument while slowly moving closer to the patient until the middle finger slightly touches their cheek.
• You will end up approximately 1.5 to 3 cm from the eye.
• In the final position, lightly touch the patient's cheek with your finger or not at all.

Posterior Segment Landmarks

• Key landmarks of the posterior segment are the optic disc, macula, superior/inferior nasal/temporal arcades.
• You can view these with direction ophthalmoscope

Limitation of Direct Ophthalmoscopy

• There is a small field of view.
• There is a lack of stereopsis.
• It is dependent on refractive error.
  • More concerned with myopes, which is nearsightedness.
• Dependent on pupil size and may need pupil to be dilated.
• Media opacities like cataracts make it more challenging.

Indirect Ophthalmoscopy

• Slit Lamp Fundus Biomicroscopy utilizes condensing lenses (78/90D).
• The fundus is seen as an aerial image that is inverted and reversed.
• Binocular Indirect ophthalmoscopy also shows the fundus in an inverted and reversed way.

Direct vs Indirect Ophthalmoscopy

• Direct ophthalmoscopy produces an unreversed or upright image at 15x magnification.
• Indirect ophthalmoscopy produces a reverse or inverted direct image.
  • The image is about 2-5x the magnification.

Review of Diabetic Retinopathy

• Important information to ascertain prior to examination includes:
  • Type and duration of DM
  • Blood sugars (Fasting / Post-prandial)
  • A1C
  • Medications used and compliance
  • How and who they see

Causes of Blindness in Diabetic Retinopathy Patients

• Clinically significant macular edema
• Pre-retinal / vitreous hemorrhage
• Retinal detachment

Classifications of Diabetic Retinopathy

• Non-Proliferative
  • Mild
  • Moderate
  • Severe
  • Very Severe
• Proliferative
  • High Risk

NPDR Classification

• There are four levels of severity: Mild, Moderate, Severe, and Very Severe.
• The determining factors are extent of intraretinal microvascular abnormalities (IRMA), venous abnormalities, and retinal hemorrhages.

Microaneurysms

• Pathologic progress includes formation of capillary microaneurysms, vascular permeability and capillary closure.

Mild Non-Proliferative Diabetic Retinopathy

• At least one microaneurysm is present.
  • Severity is less than that depicted in ETDRS standard photograph 2A.
• There are no other diabetic retinal lesions or abnormalities.
• Follow up should be in 9 months to 1 year.
• There is a 5% risk of progression to Proliferative DR.

Moderate Non-Proliferative Diabetic Retinopathy

• Microaneurysms/hemorrhages are greater than depicted in ETDRS standard photograph 2A in 1-3 retinal quadrants.
• Soft exudates, venous beading, or IRMA are definitely present.
• Cotton wool spots are indicative of retinal ischemia that causes obstruction of axoplasmic flow.
  • Subsequent swelling of disrupted axons of the RNFL give their characteristic appearance.
• Venous beading & Intraretinal Microvascular Abnormalities (IRMA)
• Follow-up should be in 6 months.
• There is a 12-27% risk of progression to PDR.

Severe Non-Proliferative Diabetic Retinopathy - 4-2-1 Rule

• Microaneurysms/hemorrhaging in all 4 quadrants
• Venous beading in 2 or more quadrants
• Severe IRMA's in one quadrant
• Follow-up should be in 3 months or retinal consult.
  • 50% develop PDR within 15 months.
• Very Severe Non-Proliferative Diabetic Retinopathy – 2 of the criteria are met.

Proliferative Diabetic Retinopathy

• It is a vascular response to retinal hypoxia
• Vascular Endothelial Growth Factor (VEGF) plays a significant role in the proliferation of neovascularization.
  • It is a chemical signal (signaling protein) produced by cells that stimulates the growth of new blood vessels.
  • It assists in restoring the oxygen supply when blood circulation is inadequate.
• When overexpressed, it may contribute to proliferative diabetic retinopathy
• Classification occurs once neovascularization occurs or if a pre-retinal or vitreous hemorrhage is present.
• Neovascularization can occur at the iris(NVI), elsewhere(NVE) on the retina, or at the disc(NVD)
• Gonioscopy should be performed in presence of neovascularization of the iris.

High Risk PDR

• Characterized by the presence of at least 3 of 4 risk factors for severe vision loss from diabetic retinopathy:
  • Pre-retinal or vitreous hemorrhage.
  • Presence of new vessels (neovascularization).
  • Presence of new vessels on or near the disc (NVD).
  • Presence of moderate or severe new vessels (NV > standard photograph 10A or NVE > 1/2 disc area.
• Obtain a retinal consult in 2-4 weeks for Non-high-risk, and in 24-48 hours for High-risk regardless of severity.
• At this time, anti-VEGF therapy is the initial treatment of choice for central-involved macular edema with vision impairment (20/32 or worse).
  • Possible subsequent or deferred focal laser treatment will occur also.

Treatment of Proliferative Diabetic Retinopathy

• Pan-retinal photocoagulation (PRP) and Argon laser applied throughout the mid-peripheral and peripheral retina, reduce the retina's need for oxygen
  • ETDRS and DRS proved benefit of immediate PRP
  • Reduces the retina's need for oxygen, decreases hypoxia, decreases vasoproliferative mediators, and regression of new vessel growth
• Anti-VEGF is also used (*can be in conjunction with laser)

Clinically Significant Macular Edema (CSME)

• The term was introduced in the Early Treatment Diabetic Retinopathy Study.
  • Retinal thickening at or within 500 microns (1/3 DD) of the center of the macula.
  • Hard exudates at or within 500 microns of the center of the macula with adjacent retinal thickening.
  • Retinal thickening greater than 1 DD in size which is within 1 DD from the center of the macula.
• Now called Diabetic Macular Edema (DME)
  • Is a collection of intraretinal fluid in the macular area, with or without lipid exudates or cystoid changes.
  • Center involved will show retinal thickening in the macula that involves the central subfield zone (1mm in diameter).
  • Non-center involved will show retinal thickening in the macula that does not involve the central subfield zone (1mm in diameter).

Treatment of Macular Edema

• Anti-VEGF treatment is the first line treatment for CSME/DME.
• An algorithm has been established: 6 monthly injections are given unless visual acuity is 20/20 or better.
  • Central Subfoveal Thickness is less then 320 microns for men and 305 microns for women
• Focal argon laser can also be used

Thyroid Eye Disease

• Also known as Graves' ophthalmopathy
  • Usually develops in people with overactive thyroid (hyperthyroidism) caused by Grave's disease.
  • Grave's disease is an autoimmune disease caused by antibodies directed against receptors present in the thyroid cells around the eyes.
  • About 25 to 50% of people with Grave's disease will have ocular symptoms: redness/pain, puffiness around the eyes, bulging of the eye, and dry eyes/irritation.
• Women are affected 8x's more than men.
• Occurs between the ages of 20 and 45
• Smoking has shown to increase severity and increased duration of ocular manifestations.
• Signs include Dalrymple's sign (lid retraction), Von Graefe's sign (lid lag on downgaze), Stellwag's sign (staring look with infrequent blinking), and Moebius' sign (Lack of convergence due to EOM restriction).

Staging of Thyroid Eye Disease

• N - No symptoms or signs
• O - Only signs – no symptoms (stare/lid lag)
• S - Soft Tissue Involvement (conjunctiva)
• P - Proptosis
• E - Extra-ocular muscle involvement
• C - Corneal Involvement
• S - Sight loss (optic neuropathy) – 5% incidence

Thyroid Eye Disease (TED)

• It is an active phase where signs and symptoms may progress and last 2-3 years, and it can be prolonged in smokers.
  • This phase is followed by a quiescent phase.
• Clinical Activity Score (CAS) is used to assess disease activity level.
  • It is a 7-point activity scale with each element worth 1 point.
  • A score of 3 or more suggests active thyroid eye disease.
• The focus of treatment is to preserve sight and integrity of the cornea.

Treatment of TED

• Tepezza (teprotumumab-trbw), the only FDA-approved treatment.
  • Tepezza is a monoclonal antibody that reduces eye swelling, exophthalmos and double vision.
  • Improvement is noted in approximately 6 weeks. -It works by blocking the action of insulin-like growth factor-1 receptor (IGF-1R), which is a protein in TED.
  • Tx is given by infusion once every 3 weeks for a total of 8 infusions (each taking 60-90 minutes).
  • After 6 months about 75% of patients reported a reduction in proptosis of 2mm.
  • Tepezza may increase sx's of inflammatory bowel disease & elevated blood sugar.
  • Other common side effects include muscle spasm, nausea, alopecia, diarrhea, fatigue hearing loss, dry skin and HA's.

Test your knowledge of diabetic retinopathy exams. Questions cover ophthalmoscopy limitations, image types, patient history, significant findings, disease stages, severity levels, and management.