Cystoid Macular Edema (CME): Causes, Treatment, and Where Integrative Care Fits

In short. Cystoid macular edema (CME) is swelling of the macula, the central retina used for reading and faces, with fluid held in small cysts. It is a pattern with many causes, including cataract surgery, uveitis, retinal vein occlusion, diabetes, some medicines and inherited conditions. Treatment depends on the cause. Many cases after cataract surgery settle with drops or on their own, while CME from uveitis or vein occlusion often needs steroids or injections. Sudden loss of vision, or a painful red eye after surgery, needs same-day care. Integrative care can sit alongside this plan but does not replace it.

What CME is. "CME" is the abbreviation eye doctors use for cystoid macular edema. In British spelling it is cystoid macular oedema, often shortened to CMO. (Outside eye care, CME usually means continuing medical education, which is unrelated.)

The usual symptoms are blurred or wavy central vision, colours that look faded, and reading that stays hard even with new glasses. An OCT scan, a quick light-based picture of the retina, shows the cysts and measures how thick the macula is. A dye test (fluorescein angiography) can show leaking vessels in a typical petal-shaped pattern and helps find the cause [1].

The main causes are:

• After cataract surgery (Irvine-Gass syndrome), the most common type. About 1-2% of people get swelling that affects vision, peaking about 6 weeks after surgery [2]. In a UK study of 81,984 eyes, the rate was 1.17% without risk factors [3]. It was higher with diabetes, an epiretinal membrane, uveitis, a past vein occlusion, retinal detachment repair or a torn lens capsule [3].
• Uveitis (inflammation inside the eye). In a study of 529 people with uveitis, a third had CME, and it caused 42% of the cases of poor vision [4].
• Retinal vein occlusion and diabetes. Leaking vessels from a blocked vein or from diabetic retinopathy can produce the same cystoid pattern.
• Medicines. These include fingolimod for multiple sclerosis, taxane chemotherapy and high-dose niacin. Glaucoma drops are also discussed below.
• Inherited and other conditions. Retinitis pigmentosa, an epiretinal membrane pulling on the macula, and retinal surgery can all cause CME.

Treatments with good evidence

CME after cataract surgery. Most cases settle within weeks to months, and many need no extra treatment [1, 2]. Usual first-line care is an anti-inflammatory (NSAID) eye drop, such as ketorolac, bromfenac or nepafenac, with a steroid drop [1]. If swelling lasts, options include steroid injections beside or into the eye, or a steroid implant [1].

The trial evidence for treating established CME is thinner than many people expect. A Cochrane review found only 7 small trials, with 266 people in total, and could not say how well NSAID drops work [5].

Preventing CME before cataract surgery. The European ESCRS PREMED trial tested prevention regimens. In 914 people without diabetes, swelling that affected vision occurred in 3.6% with bromfenac drops alone and 5.1% with dexamethasone drops alone. With both drops together, it was 1.5% [6].

In 213 people with diabetes, no one given a steroid injection (triamcinolone) under the conjunctiva at the end of surgery developed CME [7]. An added bevacizumab injection made no significant difference. If you have diabetes, uveitis or an epiretinal membrane, ask your surgeon about a prevention plan.

CME from uveitis. Controlling the inflammation comes first, with steroid drops, tablets or immune-suppressing medicines managed by a uveitis specialist. The POINT trial compared three steroid injections for uveitic macular edema [8].

At 8 weeks, thickness fell by 23% with triamcinolone beside the eye, 39% with triamcinolone into the eye and 46% with the dexamethasone implant. Both injections into the eye improved vision by about 5 letters more than the injection beside it. They carried a modestly higher risk of raised eye pressure [8].

The MERIT trial then studied 194 people whose uveitic macular edema persisted or came back [9]. At 12 weeks, thickness fell by 35% with the dexamethasone implant, 11% with methotrexate injected into the eye and 22% with ranibizumab. Only the dexamethasone group gained vision significantly, about 5 letters, though raised eye pressure was more common [9].

Steroids in or around the eye can also cause cataract, so pressure checks and follow-up matter.

CME from retinal vein occlusion or diabetes. Anti-VEGF injections are first-line. The SCORE2 trial treated 362 people with central or hemiretinal vein occlusion. Monthly bevacizumab or aflibercept for 6 months gained about 19 letters on average (18.6 and 18.9) [10]. Steroid implants are a second option.

For diabetes, see diabetic macular edema.

Treatments with some evidence

Changing a medicine that may be the cause. Only do this with the doctor who prescribed it.

• Fingolimod (Gilenya). In pooled trials in 2,615 people with multiple sclerosis, 0.3% on the 0.5 mg dose and 1.2% on 1.25 mg developed macular edema [11]. Most cases appeared within 3-4 months of starting, and 84% resolved after the drug was stopped [11]. An eye exam before starting and during treatment is recommended, especially after uveitis.
• Taxane chemotherapy. In a Japanese study of 14,260 people, 0.21% developed macular edema, more often with nab-paclitaxel (0.43%) [12]. In those who stopped the drug, swelling and vision improved within about 2 months [12]. This decision belongs to your oncologist, weighed against cancer control.
• High-dose niacin (nicotinic acid). Niacin taken for cholesterol can cause a cystoid maculopathy, first described in 1973 [13]. Tell your eye doctor if you take it.
• Prostaglandin glaucoma drops (such as latanoprost). These have been linked to CME after cataract surgery in reports. A systematic review of 4 randomised trials, and the large UK database, found no raised risk after uncomplicated surgery [3, 14]. Do not stop glaucoma drops on your own; ask your surgeon.

CME with retinitis pigmentosa. This is usually treated with carbonic anhydrase inhibitors: acetazolamide tablets or dorzolamide drops. A systematic review of 23 studies found oral acetazolamide had the strongest support [15]. But the studies were small, and swelling often came back over time.

What is not proven

• Acupuncture and herbal medicine. We have not found controlled trials showing that acupuncture, Chinese herbs or Ayurvedic herbs reduce CME or improve vision. The published reports are single cases or small uncontrolled studies.
• Supplements, diets and drops sold for "macular swelling". None has been tested properly in CME. Taking them is not a reason to skip drops or follow-up scans.
• Anything that asks you to delay or stop prescribed treatment. This includes stopping steroid or NSAID drops early. Swelling that lasts for months can damage the macula for good, so delay has a real cost.

Where Netra fits

Netra Eye Institute is an acupuncture and Oriental medicine practice. We do not diagnose or treat cystoid macular edema, and we do not replace your eye surgeon, retina specialist or uveitis specialist. Our role is adjunctive:

• We check the basics with your doctors: a known cause, a scan schedule, and which drops to use and for how long.
• We offer acupuncture and, where appropriate, Chinese herbal medicine within Netra Restoration Therapy (NRT), with the evidence explained before you start. Herbs are reviewed against your medicines, including immune-suppressing drugs for uveitis, multiple sclerosis medicines, chemotherapy and blood thinners.
• We do not needle near an eye that has recently had surgery or an injection. We never ask you to change steroid, NSAID or glaucoma drops. If you are on steroids, we check that your eye pressure checks are booked.
• We share what we see with your eye doctor. We refer you back the same day if you have a painful red eye or a sudden drop in vision.

For Ayurvedic approaches, see Ayurvedic treatment for macular edema.

NRT is not a treatment for cystoid macular edema and does not replace eye drops, steroids, injections or your eye doctor's care. If you want to talk through whether integrative care makes sense alongside your treatment, request a consultation.

Questions people ask

What does CME mean in ophthalmology?

CME stands for cystoid macular edema: swelling of the macula with fluid in small cysts. The British term is cystoid macular oedema (CMO). It describes what the retina looks like, so the next question is always what caused it.

What causes CME?

The most common cause is recent cataract surgery. Others are uveitis, retinal vein occlusion, diabetes, some medicines, retinitis pigmentosa and an epiretinal membrane. Your eye doctor works out the cause from your history, the OCT scan and sometimes a dye test.

What does CME look like on OCT?

OCT shows dark, rounded fluid spaces within the layers of the central retina, and the macula looks thicker than normal [1]. After cataract surgery, OCT picks up mild thickening in up to 40% of eyes, most of which never affects vision [2]. On a dye test, the leakage often forms a petal-shaped pattern around the centre [1].

Does CME go away, and what is the prognosis?

It depends on the cause. Most CME after cataract surgery resolves within weeks to months [1, 2]. CME from uveitis, vein occlusion or diabetes often responds to treatment but can come back, so follow-up scans continue.

Is cystoid macular edema the same as macular edema?

Macular edema means any swelling of the macula. "Cystoid" means the fluid sits in small cysts, which is one common pattern. Diabetic macular edema is one cause that can show this pattern.

References

1. Zur D, Loewenstein A. Postsurgical cystoid macular edema. Dev Ophthalmol. 2017;58:178-190.
2. Orski M, Gawęcki M. Current management options in Irvine-Gass syndrome: a systemized review. J Clin Med. 2021;10(19):4375.
3. Chu CJ, Johnston RL, Buscombe C, et al. Risk factors and incidence of macular edema after cataract surgery: a database study of 81984 eyes. Ophthalmology. 2016;123(2):316-323.
4. Lardenoye CW, van Kooij B, Rothova A. Impact of macular edema on visual acuity in uveitis. Ophthalmology. 2006;113(8):1446-1449.
5. Sivaprasad S, Bunce C, Crosby-Nwaobi R. Non-steroidal anti-inflammatory agents for treating cystoid macular oedema following cataract surgery. Cochrane Database Syst Rev. 2012;(2):CD004239.
6. Wielders LHP, Schouten JSAG, Winkens B, et al. European multicenter trial of the prevention of cystoid macular edema after cataract surgery in nondiabetics: ESCRS PREMED study report 1. J Cataract Refract Surg. 2018;44(4):429-439.
7. Wielders LHP, Schouten JSAG, Winkens B, et al. Randomized controlled European multicenter trial on the prevention of cystoid macular edema after cataract surgery in diabetics: ESCRS PREMED study report 2. J Cataract Refract Surg. 2018;44(7):836-847.
8. Thorne JE, Sugar EA, Holbrook JT, et al. Periocular triamcinolone vs. intravitreal triamcinolone vs. intravitreal dexamethasone implant for the treatment of uveitic macular edema: the PeriOcular vs. INTravitreal corticosteroids for uveitic macular edema (POINT) trial. Ophthalmology. 2019;126(2):283-295.
9. Multicenter Uveitis Steroid Treatment Trial (MUST) Research Group; Acharya NR, Vitale AT, Sugar EA, et al. Intravitreal therapy for uveitic macular edema: ranibizumab versus methotrexate versus the dexamethasone implant: the MERIT trial results. Ophthalmology. 2023;130(9):914-923.
10. Scott IU, VanVeldhuisen PC, Ip MS, et al. Effect of bevacizumab vs aflibercept on visual acuity among patients with macular edema due to central retinal vein occlusion: the SCORE2 randomized clinical trial. JAMA. 2017;317(20):2072-2087.
11. Zarbin MA, Jampol LM, Jager RD, et al. Ophthalmic evaluations in clinical studies of fingolimod (FTY720) in multiple sclerosis. Ophthalmology. 2013;120(7):1432-1439.
12. Tsujinaka H, Imoto S, Ueda T, et al. Incidence and prognosis of taxane-induced macular edema: a retrospective study from the Japan Clinical REtina Study Group (J-CREST). Sci Rep. 2024;14(1):19530.
13. Gass JD. Nicotinic acid maculopathy. Am J Ophthalmol. 1973;76(4):500-510.
14. Santamaria AB, Vera L, Rebollo F, Hartleben-Matkin C. Cystoid macular edema related to uncomplicated cataract surgery and topical prostaglandin analogs: a systematic review of randomized controlled trials. Cureus. 2024;16(11):e72920.
15. Bakthavatchalam M, Lai FHP, Rong SS, et al. Treatment of cystoid macular edema secondary to retinitis pigmentosa: a systematic review. Surv Ophthalmol. 2018;63(3):329-339.