Retinitis - Hyperexcision

Last updated: November 14, 2024

Table Of Contents

Overview
CMV Retinitis
Toxoplasma Retinitis
Candida Retinitis
Acute Retinal Necrosis (ARN)
Progressive Outer Retinal Necrosis (PORN)
Other Causes of Retinitis

Overview

Retinitis occurs in conditions that cause retinal inflammation, resulting in edema and necrosis. Patients typically experience floaters (dark spots in the visual fields) and decreased vision. Infectious retinitis is usually a manifestation of systemic illness. Cytomegalovirus is a classic cause of retinitis. It is typically associated with immunocompromised patients (e.g. HIV/ AIDs patients with a CD4 count < 50, transplant patients on immunosuppression). It is crucial to rapidly diagnose and treat retinitis to decrease the risk of infection of the contralateral eye and blindness.

Ocular signs and symptoms
- Blurry vision
- Floaters
- Symptoms consistent with retinal detachment (pain may or may not be present)
Hallmark changes on fundoscopy
- Retinal haemorrhages
- Whitish appearance to the retina

CMV Retinitis

CMV causes retinitis in immunocompromised patients or through vertical transmission. CMV can cause an acute loss of vision

90-100% of the population carries CMV. However, majority are asymptomatic. It is rare to find ocular manifestations of CMV in immunocompetent patients.

Type of CMV infection	Pt Hx	Signs and Symptoms
Congenital CMV infection	Baby of mother with acute CMV infection in pregnancy	LBW, microcephaly, petechial rash, seizures, Hepatosplenomegaly, jaundice, cataracts
CMV infection	Immunocompromised patient (AIDS, transplant, cancer, dialysis)	Liver failure, CMV colitis, esophagitis, pneumonia, retinitis

Signs and symptoms
- Blurry vision
- Floaters
- Retinal detachments
Investigations
- Fundoscopy
  - White, granular plaque with irregular borders (crosses through the veins)
  - Hemorrhaging
- CMV titres: from blood or vitreous
- HIV serology
- CD4+ count: for patients who are at risk of HIV
Treatment
- IV Ganciclovir
- HIV positive patients should be started on HAART

Toxoplasma Retinitis

Toxoplasma gondii causes infection in both immunocompetent and immunocompromised patients. However retinitis typically manifests in immunocompromised patients and in children through vertical transmission. It is transmitted horizontally through exposure to cat litter, undercooked meat and eggs, or unwashed vegetables.

Signs and symptoms of acute toxoplasmosis Mild flu-like symptoms
- Fever
- Muscle aches
- Lymphadenopathy
‘Signs and symptoms in immunocompromised patients
- Encephalitis
- Dermatologic symptoms
Signs and symptoms of congenital infection
- LBW
- Prematurity
- Jaundice
- Hepatosplenomegaly
- Cataract
- Neurologic deficit
Ocular signs and symptoms
- Decreased visual acuity
- Floaters
Investigations
- Fundoscopy
  - White fluffy lesion in active retinitis
  - Darkened lesions (scar)
  - Vitreous haze
- Toxoplasma titres: to determine active infection (IgG vs IgM)
Treatment
- Pyrimethamine and Sulfadiazine
  - Can also be given to immunocompromised patients as prophylaxis
- Corticosteroids (in active infection to reduce inflammation)
- Pregnant women receive Spiramycin to reduce risk of transmission to the fetus

Candida Retinitis

Candida retinitis is the most common fungal infection in the eye. It is typically seen in newborns and other patients with specific risk factors.

Risk factors
- IV drug use
- Recent major surgery
- Recent sepsis
- Indwelling catheter
- Dialysers
- Cancer patients
- Diabetics
- Newborns of mothers with Candida in the birth canal
Signs and symptoms
- Decreased visual acuity
- Floaters
- Photophobia
- Pain (candida also affects other structures of the eye)
- Anterior uveitis (red eye)
Investigations
- Funduscopy
  - Dense, white fluffy mass
  - Obscured with notable vitreous haze
Treatment
- Amphotericin B and Flucytosine

Candida Retinitis. Source: American Academy of Ophthalmology

Acute Retinal Necrosis (ARN)

ARN is a sudden infection in young, immunocompetent patients caused by HSV or VZV. It presents with the typical retinitis symptoms. Prognosis is poor.

Investigations
- Fundoscopy
  - Patchy white necrosis
  - “Holes” in the peripheral retina progressing towards the posterior pole
Treatment
- Acyclovir
- Corticosteroids and Aspirin

Acute retinal necrosis. Source: Eyes for Ears

Progressive Outer Retinal Necrosis (PORN)

PORN is also due to VZV and HSV. It presents similar to ARN but occurs in immunocompromised patients (HIV/AIDS). Prognosis is also poor.

Investigations
- Fundoscopy
  - Homogenous necrosis of the retina
  - ”Cracked mud” appearance due to Perivenular sparing (inflammation does not go through the venules and arterioles)
  - Cherry red spot
Treatment
- Ganciclovir + Foscarnet IV

Other Causes of Retinitis

Cryptococcus Retinitis

Syphilis Retinitis

TB Retinitis

Reference Intervals ›

Biochemistry

ACTH	P: <80 ng/L
ALT	P: 5–35 U/L
Albumin	P: 35–50 g/L
Aldosterone	P: 100–500 pmol/L
Alk. phosphatase	P: 30–130 U/L
α-Amylase	P: 0–180 IU/dL
α-Fetoprotein	S: <10 kU/L
Angiotensin II	P: 5–35 pmol/L
ADH	P: 0.9–4.6 pmol/L
AST	P: 5–35 U/L
Bicarbonate	P: 24–30 mmol/L
Bilirubin	P: 3–17 μmol/L
BNP	P: <50 ng/L
CRP	P: <10 mg/L
Calcitonin	P: <0.1 mcg/L
Calcium (ionized)	P: 1.0–1.25 mmol/L
Calcium (total)	P: 2.12–2.60 mmol/L
Chloride	P: 95–105 mmol/L
Cholesterol	P: <5.0 mmol/L
VLDL	P: 0.128–0.645 mmol/L
LDL	P: <2.0 mmol/L
HDL	P: 0.9–1.93 mmol/L
Cortisol AM	P: 450–700 nmol/L
Cortisol Midnight	P: 80–280 nmol/L
CK ♂	P: 25–195 U/L
CK ♀	P: 25–170 U/L
Creatinine	P: 70–100 μmol/L
Ferritin	P: 12–200 mcg/L
Folate	S: 2.1 mcg/L
FSH	P: 2–8 U/L ♂; >25 menopause
GGT ♂	P: 11–51 U/L
GGT ♀	P: 7–33 U/L
Glucose (fasting)	P: 3.5–5.5 mmol/L
Growth hormone	P: <20 mu/L
HbA1C (DCCT)	B: 4–6%
HbA1C (IFCC)	B: 20–42 mmol/mol
Iron ♂	S: 14–31 μmol/L
Iron ♀	S: 11–30 μmol/L
Lactate (venous)	P: 0.6–2.4 mmol/L
Lactate (arterial)	P: 0.6–1.8 mmol/L
LDH	P: 70–250 U/L
LH	P: 3–16 U/L
Magnesium	P: 0.75–1.05 mmol/L
Osmolality	P: 278–305 mosmol/kg
PTH	P: 0.8–8.5 pmol/L
Potassium	P: 3.5–5.3 mmol/L
Prolactin ♂	P: <450 U/L
Prolactin ♀	P: <600 U/L
PSA	P: 0–4 mcg/mL
Protein (total)	P: 60–80 g/L
Red cell folate	B: 0.36–1.44 μmol/L
Renin (erect)	P: 2.8–4.5 pmol/mL/h
Renin (recumbent)	P: 1.1–2.7 pmol/mL/h
Sodium	P: 135–145 mmol/L
TBG	P: 7–17 mg/L
TSH	P: 0.5–4.2 mU/L
T4	P: 70–140 nmol/L
Free T4	P: 9–22 pmol/L
TIBC	S: 54–75 μmol/L
Triglycerides	P: 0.50–2.3 mmol/L
T3	P: 1.2–3.0 nmol/L
Troponin T	P: <0.1 mcg/L
Urate ♂	P: 210–480 μmol/L
Urate ♀	P: 150–390 μmol/L
Urea	P: 2.5–6.7 mmol/L
Vitamin B12	S: 0.13–0.68 nmol/L
Vitamin D	S: 50 nmol/L

Arterial Blood Gases

pH	7.35–7.45
PaCO₂	4.7–6.0 kPa
PaO₂	>10.6 kPa
Base excess	±2 mmol/L

Urine

Cortisol (free)	<280 nmol/24h
Hydroxyindole acetic acid	16–73 μmol/24h
Hydroxymethylmandelic acid	16–48 μmol/24h
Metanephrines	0.03–0.69 μmol/mmol cr.
Osmolality	350–1000 mosmol/kg
17-Oxogenic steroids ♂	28–30 μmol/24h
17-Oxogenic steroids ♀	21–66 μmol/24h
17-Oxosteroids ♂	17–76 μmol/24h
17-Oxosteroids ♀	14–59 μmol/24h
Phosphate (inorganic)	15–50 mmol/24h
Potassium	14–120 mmol/24h
Protein	<150 mg/24h
Protein/creatinine ratio	<3 mg/mmol
Sodium	100–250 mmol/24h

Haematology

WCC	4.0–11.0 ×10⁹/L
RBC ♂	4.5–6.5 ×10¹²/L
RBC ♀	3.9–5.6 ×10¹²/L
Hb ♂	130–180 g/L
Hb ♀	115–160 g/L
PCV ♂	0.4–0.54 L/L
PCV ♀	0.37–0.47 L/L
MCV	76–96 fL
MCH	27–32 pg
MCHC	300–360 g/L
RDW	11.6–14.6%
Neutrophils	2.0–7.5 ×10⁹/L (40–75%)
Lymphocytes	1.0–4.5 ×10⁹/L (20–45%)
Eosinophils	0.04–0.44 ×10⁹/L (1–6%)
Basophils	0–0.10 ×10⁹/L (0–1%)
Monocytes	0.2–0.8 ×10⁹/L (2–10%)
Platelets	150–400 ×10⁹/L
Reticulocytes	0.8–2.0% / 25–100 ×10⁹/L
Prothrombin time	10–14 s
APTT	35–45 s

Paediatric

Pulse Rate (bpm)
Neonate	140–160
Infant <1yr	120–140
1–5 years	110–130
5–12 years	80–120
>12 years	70–100
Respiratory Rate (tachypnoea)
0–2 months	≥60/min
2–12 months	≥50/min
1–5 years	≥40/min
>5 years	≥30/min
Blood Pressure (mmHg)
Term	65/45
1 year	75/50
4 years	85/60
8 years	95/65
10 years	100/70
Weight Formulas
3–12 months	(a + 9)/2 kg
1–6 years	2a + 8 kg
>6 years	(7a − 5)/2 kg
Haemoglobin (g/dL)
Term newborn	13–20
1 month	11–18
2 months	10–15
1–2 years	10–13
>2 years	11–14
MUAC (6 months–5 years)
Obese	>17.5 cm
Normal	13.5–17.4 cm
At risk	12.5–13.4 cm
Moderate malnutrition	11.5–12.4 cm
Severe malnutrition	<11.5 cm
Developmental Milestones
Social smile	1.5 months
Head control	4 months
Sits unsupported	7 months
Crawls	10 months
Stands unsupported	10–12 months
Walks	12–13 months
Talks	18 months
CSF WBC (/mm³)
Term newborn	0–25
>2 weeks	0–5

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