Dry eye affects the cataract surgery patient in all aspects: planning, outcome and patient satisfaction. Optimization of the ocular surface during the preoperative evaluation is critical to ensure a successful outcome and a happy patient. Yet ocular surface assessment still has not become a formal part of the preoperative cataract surgery process for all practitioners.

Often times, dry eye disease (DED) is hard to diagnose, frustrating to treat and difficult to study, so we need to find accurate ways to identify the cataract surgery candidate who will be saddled with post-operative dry eye.

Here is an update on where the literature stands today.

PREOPERATIVE DIAGNOSTIC EVALUATION

Dry eye’s importance

Dry eye plays a key role in patient satisfaction after cataract surgery — sometimes even more so than visual acuity outcome. Szakáts et al. studied two small groups of patients after their cataract surgery: satisfied and unsatisfied.¹ The two groups showed no difference in the postoperative BCVA and UCVA. Notably, almost all of the commonly used dry eye tests (tear meniscus height, Schirmer 1, corneal staining and meibomian gland evaluation), with the exception of tear breakup time, had no correlation with visual function or patient satisfaction.

However, dry eye symptoms and overall health anxiety were the most significant predictors of patient satisfaction. Szakáts et al. took one step back to take in an even bigger picture, and found that results of a generalized health anxiety questionnaire correlated with dry eye symptoms. These symptoms were more predictive of patient satisfaction following cataract surgery than any objective measurement of visual acuity or signs of dry eye, highlighting an underlying psychological component that has so far been under-addressed.¹

When looking at our practices, we can see that this demonstrates the importance of addressing overall ocular surface health proactively (rather than reactively). This paper highlights what we already know — signs do not always correlate to symptoms and vice versa. Physicians should individualize their assessments and treatments for these patients. Also, we should recognize the importance of optimization of the ocular surface in patient satisfaction post-cataract surgery.

SPOTLIGHT ON MEIBOMIAN GLAND DYSFUNCTION (MGD)

First among equals?

The reasons why dry eye worsens after cataract surgery are numerous – from transection of corneal nerves, introduction of preservative-containing topical eye drops, intraoperative exposure to the microscope light, iodine prep, and limited ability to perform lid hygiene in the immediate postoperative setting.² A few recent studies highlight MGD as a potential key player in perioperative dry eye exacerbation.

Park et al. evaluated meibomian gland function before and after cataract surgery and found that meibomian gland dysfunction correlated with the patient’s ocular symptoms score following cataract surgery.³ Meibomian gland function was evaluated based on expressibility of meibomian glands and all morphological changes of the meibomian glands. After cataract surgery, it was found that patients with pre-existing DED had increased meibomian gland abnormalities compared to patients without dry eye. Furthermore, meibomian gland structural changes persisted out to two months postoperatively.

The cytokine factor

Jung et al. measured levels of cytokines in the tear film pre- and postoperatively and found that inflammatory cytokine levels correlated with severity of meibomian gland dysfunction.4 Patients with pre-existing MGD had elevated IL-2, IL-6 and TNF-alpha levels at baseline. Furthermore, patients with significant preoperative meibomian gland dysfunction experienced a more significant exacerbation of MGD postoperatively compared to those with minimal to mild pre-existing MGD. These patients also experienced a surge in inflammatory cytokines, especially IL-6 and TNF-alpha; this surge was considered an indicator of severe MGD aggravation in patients with preoperative MGD. Additionally, cytokine levels correlated with Ocular Surface Disease Index (OSDI) score.

One theory to unite them all?

While MGD, evaporative dry eye and aqueous insufficiency have classically been considered as separate causes of dry eye, Rynerson and Perry have recently proposed a single unification theory for dry eye and blepharitis: “Dry Eye Blepharitis Syndrome.”⁵ They propose that underlying dry eye is an inflammatory process driven by inflammatory virulence factors produced by our biofilm once it achieves a critical population of toxin-producing bacteria, namely staphylococcus aureus and s. epidermidis. Biofilm-forming bacteria can survive a surgical betadine prep. Since the lid margin is one of the most neglected areas of the body to receive hygienic attention, Rynerson and Perry propose that all patients receive an electromechanical debridement of their lids after the age 50, similar to routine dental cleaning.

MGD is becoming a more recognized culprit to DED. In our practice, the vast majority of dry eye patients have some component of MGD. Postoperative patients commonly have the appearance of an MGD flare. This observation is supported by the studies cited above.

FUTURE DIRECTION

Diagnostics forecast

The correlation of tear cytokine levels with meibomian gland dysfunction and visual function is an encouraging starting point for the development of future diagnostic and treatment modalities. However, we currently lack reliable objective methods to diagnose clinical and subclinical DED. So, we must give close attention to the subjective evaluation of dry eye disease through visual-function questionnaires and patient discussion.

Many ophthalmologists use visual-function questionnaires to assess dry eye symptoms; however, we still have no standard for the diagnostic approach to the perioperative dry eye patient.2 For example, the OSDI is one of the most widely utilized visual-function questionnaires, but it falls short in the preoperative cataract surgery setting as several of its questions overlap with those of visually significant cataract.

Park et al. and Szakáts et al addressed this difficulty in their research studies by modifying the questionnaire to exclude items related to decreased visual acuity^1,3; they eliminated the two questions that addressed blurred vision, “because it was hard to discriminate the change of symptoms caused by cataract surgery alone or combined with visual symptoms due to dry eye that was induced by phacoemulsification.”³ González-Mesa et al. addressed this conundrum by only including in their study those patients with unilateral cataract and good visual acuity in the non-operative eye.⁶

Lack of standardized evaluation of pre-operative dry eye limits our ability to study and diagnose the symptomatic patient. A pre-operative visual function and dry eye questionnaire that additionally address psychological stressors and risk factors for dry eye may help to identify patients who are at risk of postoperative symptomatic dry eye—even with minimal ocular signs.

Think long term

Early treatment of the subclinical DED patient — once identified — in the immediate preoperative setting helps to maximize cataract surgery outcome.

The earlier that the subclinical DED patient can be identified before surgery, and hence receive early treatment, helps to maximize the cataract surgery outcome.

This ensures high-quality biometry, optimizes patient satisfaction and preemptively treats the worsening of dry eye following cataract surgery. It is our practice to incorporate lubricant eye drops, lid hygiene and omega-3 fatty acids in the majority of patients’ regular preoperative regimen (even years prior to their cataract becoming visually significant). Additionally, we must remember to pay attention to the lid margin and address any evidence of pre-existing MGD.

CONCLUSION

DED is a chronic multifactorial condition that requires long-term postoperative management. While inflammatory cytokines return to preoperative baseline levels two months after cataract surgery, the recent study by Park et al. showed that meibomian gland structural abnormality persisted even at two months.³ We don’t know how long the exacerbation of dry eye and MGD lasts following cataract surgery, but we should not abandon our cataract surgery patient after the immediate postoperative period.

We must be cognizant of the complexity of symptoms in DED, stratify our at-risk patients and appropriately counsel them on an individual basis. OM

REFERENCES

1. Szakáts I, Sebestyén M, Tóth É, Purebl G. Dry eye symptoms, patient-reported visual functioning, and health anxiety influencing patient satisfaction after cataract surgery. Curr Eye Res. 2017;42:832-836.
2. Barabino S, Labetoulle M, Rolando M, Messmer EM. Understanding symptoms and quality of life in patients with dry eye syndrome. Ocul Surf. 2016;14:365-376.
3. Park Y, Hwang HB, Kim HS. Observation of influence of cataract surgery on the ocular surface. PLoS ONE. 2016;11:e0152460.
4. Jung JW, Han SJ, Nam SM, Kim TI, et al. Meibomian gland dysfunction and tear cytokines after cataract surgery according to preoperative meibomian gland status. Clin Experiment Ophthalmol. 2016;44:555-562.
5. Rynerson JM, Perry HD. DEBS - a unification theory for dry eye and blepharitis. Clin Ophthalmol. 2016;10:2455-2467.
6. González-mesa A, Moreno-arrones JP, Ferrari D, Teus MA. Role of tear osmolarity in dry eye symptoms after cataract surgery. Am J Ophthalmol. 2016;170:128-132.
7. Salkovskis, P.M., Rimes, KA, Warwick, HMC, Clark, DM. The health anxiety inventory: The development and validation of scales for the measurement of health anxiety & hypochondriasis. Psychological Medicine 2002; 32:843-853.

About the Authors

SUMIT (SAM) GARG, MD is vice chair of Clinical Ophthalmology, medical director, and an associate professor in Cataract, Refractive, External Disease and Corneal Surgery at the Gavin Herbert Eye Institute at the University of California, Irvine. He can be reached at gargs@uci.edu. Financial disclosures: Consultant to Alcon, Allergan, Shire, TearScience.

Kate C. Xie, MD is a second-year resident at the Gavin Herbert Eye Institute. She can be reached at kcxie@uci.edu. No financial disclosures.